Saturday

June 25, 2016
Total # Posts: 1,994

**SCIENTIFIC NOTATION**

What we'll do is divide 1.3 x 10^8 by 8.8 x 10^5: 1.3 x 10^8 / 8.8 x 10^5 We can rewrite 1.3 x 10^8 such that the exponent of 10 is 5. To do this, move the decimal point 3 places to the right. Why 3 places? It's because 8-5 = 3: 1.3 x 10^8 = 1300 x 10^5 Then, 1300 x 10...
*April 15, 2015*

**math plz help**

Well it's a conditional probability. You have to multiply the probability of the first event to the probability of the second event for this kind of problem. If the question asked for the probability of choosing a red OR a blue marble, then their probabilities are added. ...
*April 15, 2015*

**math plz help**

Total marbles = 43 P(red) = 8 / 43 Since it was replaced, the total number of marbles is the same for the second choosing of marble. P(blue) = 12 / 43 Probability of getting a red, then a blue: 8/43 * 12/43 = 96/1849 (letter D)
*April 15, 2015*

**ALGEBRA PLSSSSSS**

To get the inverse, what you'll do is: (1) let f(x)=y, and replace x with y and y with x: f(x) = (8 - 2x)^2 y = (8 - 2x)^2 x = (8 - 2y)^2 (2) solve for y, and substitute back the y=f(x): x = (8 - 2y)^2 sqrt(x) = 8 - 2y sqrt(x) - 8 = -2y y = (sqrt(x) - 8) / (-2) y = (8 - ...
*April 15, 2015*

**geometry/trig**

Let x = original side length (ladder-wall) Let y = original side length (ladder-floor) Well yeah. The new length of the side of the triangle (where ladder touches the wall) is x - 8. The new length of side of triangle (where ladder touches the floor) is y + 16. Of course, y is...
*April 15, 2015*

**math**

Let x = length Let 3/4x = width Area of rectangle is length times width. A = l * w Substituting: 432 = x (3/4x) Solve for x: 432 = (3/4) x^2 x^2 = 432 * 4/3 x^2 = 576 x = 24 ft. (length) 3/4x = 18 ft. (width) hope this helps `u`
*April 15, 2015*

**Math**

1. Not it's actually in Quadrants II and IV. In Q I and III, the coordinates of the point have the same sign. For instance, Quadrant I: (2,4) Quadrant III: (-1,-3) 2. Yes that's right. `u`
*April 14, 2015*

**PHYSICS1**

There's a problem similar to this. I'll just repost it here: Range of projectile formula: R = vo^2 sin(2θ) / g where θ = angle vo - initial velocity g = acceleration due to gravity = 9.8 m/s^2 substitute the values to get the range: R = (18^2) * sin(2*75°...
*April 14, 2015*

**physics**

Range of projectile formula: R = vo^2 sin(2θ) / g where θ = angle vo - initial velocity g = acceleration due to gravity = 9.8 m/s^2 substitute the values to get the range: R = (18^2) * sin(2*75°) / 9.8 R = ? Make sure your calculator is in Degrees mode, not ...
*April 13, 2015*

**chemistry**

You have to have the following values. These can be found in google or in textbooks: *specific heat capacity of ice (c,ice) in J/g-K *latent heat of fusion for water (Hf) in J/g *specific heat capacity of water (c,water) in J/g-K Then substitute them in the summation of all ...
*April 13, 2015*

**Math**

A. Yeah, almost. :) d = rt Since d = 72 miles and t = 1.5 hours or 90 minutes, 72 = 1.5r (if you want r to have units in miles/hour) 72 = 90r (if you want r to have units in miles/minute) B. 72 = 1.5r r = 72/1.5 r = 48 miles/hour 72 = 90r r = 72/90 r = 0.8 mile/min
*April 13, 2015*

**Math 1**

Let x = width Let x + 6 = length Area of rectangle is just width x length. Thus, A = w * l 16 = x(x+6) 16 = x^2 + 6x x^2 + 6x - 16 = 0 Factor: (x + 8)(x - 2) = 0 x = -8 (extraneous root since dimensions cannot be negative) x = 2 inches (width) x+6 = 8 inches (length) hope this...
*April 13, 2015*

**Physics**

Use the formula to get the time: x = vo,x * t where x = horizontal distance vo,x = initial horizontal velocity t = time 47.9 = 12 * t t = 47.9 / 12 t = 3.99 s Then use this formula to get the height of cliff: h = vo,y * t - (1/2)gt^2 where h = height vo,y = initial vertical ...
*April 13, 2015*

**Math**

This problem is similar to the one you posted before. Take two points. For instance, the first two points, (0,1) and (1,4). Get the slope: m = (y2 - y1) / (x2 - x1) m = (4 - 1) / (1 - 0) m = 3 / 1 m = 3 slope-intercept form: y - y1 = m(x - x1) y - 1 = 3(x - 0) Just simplify ...
*April 13, 2015*

**Math**

To do this, just add the numerical coefficient of the variable x. The numerical coefficient is the number before the variable. In this case, its 1/2 in the term 1/2x, and 2/3 in the term 2/3x. (1/2)x + (2/3)x = (3/6)x + (4/6)x = (3 + 4)/6 x = (7/6)x
*April 13, 2015*

**Math**

I will let n = x. Take two points. For instance, the first two points, (3,2) and (4,1). Get the slope: m = (y2 - y1) / (x2 - x1) m = (2 - 1) / (3 - 4) m = 1 / -1 m = -1 slope-intercept form: y - y1 = m(x - x1) y - 2 = -1(x - 3) y - 2 = -x + 3 y = -x + 3 + 2 y = -x + 5 hope ...
*April 13, 2015*

**science**

*sorry, I mean 4.5 / 129.5 = 3.47 % v/v
*April 13, 2015*

**science**

Add the volumes together: V,total = 125 + 4.5 = 129.5 m^3 Since alcohol is 4.5 m^3, the v/v % is V,alcohol / V,total = 4.5 / 129.5 * 100 = 3.6 %
*April 13, 2015*

**chemistry**

I see. No, the 12.5 g shouldn't have any denominator units. The given was only 12.5 g NaOH, and this is the mass of NaOH. You should write, [ 12.5 g NaOH * (1 mol NaOH / 40 g NaOH) ] / [ 625 mL * (1 L / 1000 mL) ] = 0.500 M Sorry for the late reply. Hope this helps~ `u`
*April 13, 2015*

**chemistry**

If you mean that the 12.5 NaOH is 12.5 grams of NaOH, then your answer and solution are correct. :)
*April 13, 2015*

**math**

Let alpha = a Let beta = b Because it's easier to type a and b, than copy-pasting alpha and beta symbols. Anyway, recall that for a quadratic equation in the form y = ax^2 + bx + c The sum and product of the roots can be determined as such: y = x^2 - (sum)x + (product) Of ...
*April 12, 2015*

**PRE - CALCULUS**

Yes it's D.
*April 12, 2015*

**Math**

5 ft : 135° = x ft : 360° 5/135 = x/360 x = 40/3 ft This is the whole length of the circle or the circumference. To get the radius, C = 2πr r = C / 2π r = 40/3 / (2*3.14) r = 2.12 ft
*April 12, 2015*

**MATH**

Why is that? Anyway, let's solve for y. I'll multiply the first equation by -2 instead of 2: (5x - 4y = -3) * -2 ---> -10x + 8y = 6 (2x + 7y = 5) * 5 ---> 10x + 35y = 25 Add them together: -10x + 8y = 6 10x + 35y = 25 ---------------------- 43y = 31 y = 31/43 Now...
*April 12, 2015*

**MATH**

You're doing the elimination method right. :) But there's just some errors in multiplying. In your first equation (5x - 4y = -3), you multiplied it by 2. 5x * 2 = 10x, yes that's right. -4y * 2 = -8y, not -12y as you've typed. -3 * 2 = -6, not 6 as you've ...
*April 12, 2015*

**Physics**

We use the formula: h = vo,y*t - (1/2)gt^2 where h = height vo,y = initial vertical velocity t = time g = acceleration due to gravity = 9.8 m/s^2 Since there is no vertical velocity involved, vo,y = 0. If that's not very clear, we can say that vo,y = vo*sin(angle). But the...
*April 12, 2015*

**Physics**

For the horizontal: x = vo,x * t where x = horizontal distance vo,x = initial horizontal velocity t = time x = 1100 m/s * 0.32 s x = 352 m For the vertical: h = vo,y * t - (1/2)gt^2 where h = height vo,y = initial vertical velocity (which is zero) g = acceleration due to ...
*April 12, 2015*

**WORD PROBLEM HELP**

Volume of a cylinder: V = π(r^2)(h) where π = 3.14 r = radius h = height I think this is just trial and error. For instance, take r =2 and h=6: V = π(2^2)(6) V = 3.14 * 4 * 6 V = 75.36 m^3 This is one that satisfies the requirements. Just take a value of r and h...
*April 12, 2015*

**Pre - CALCULUS**

Yes, it's D. Though it's hard to show 3x3 Cramer's rule here. ;u;
*April 11, 2015*

**Math**

Note that when a number is raised to a negative exponent, we can make its exponent positive by getting its reciprocal. Some examples: 2^-1 = 1/(2^1) = 1/2 3^-2 = 1/(3^2) = 1/9 2^-3 = 1/(2^3) = 1/8 Let's simplify each choice. A. 3^-3 * 2^3 = ( 1/(3^3) ) * 2^3 = (1/27) * 8...
*April 11, 2015*

**Math**

Speed is distance traveled over time, or v = d/t Since we're solving for time, we can rearrange the formula for time: t = d/v Substitute the values. t = 2.25 x 10^6 / 1.8 x 10^4 t = ? Units in hours. Hope this helps~ `u`
*April 11, 2015*

**Math**

Take two points from the given. For instance the first two points (-4,0) and (-2,-4). Get the slope using the formula, m = (y2 - y1) / (x2 - x1) where (x1,y1) and (x2,y2) are points on the line. Substituting, m = (0 - (-4)) / (-4 - (-2)) m = (0 + 4) / (-4 + 2) m = 4 / -2 m = -...
*April 11, 2015*

**Calculus**

Area of triangle: A = (1/2)bh When A = 97 and h = 10.5, A = (1/2)bh 97 = (1/2)(b)(10.5) b = 18.48 Differentiate area with respect to time: A = (1/2)bh dA/dt = (1/2)( h*db/dt + b*dh/dt ) Substitute the values: 4 = (1/2)( 10.5*db/dt + 18.48*2) Solve for db/dt. hope this helps~ `u`
*April 11, 2015*

**Math**

Use pythagorean theorem: c^2 = a^2 + b^2 Substitute the given values, c = slant height, a = 1/2 of length of one side of the base: 9^2 = 6^2 + b^2 b = ?
*April 11, 2015*

**pre - CALCULUS**

No it's not. Multiply -4 separately to all terms inside the bracket.
*April 11, 2015*

**pre - CALCULUS**

Yes it's B, since it can be seen clearly that the simplified version of the second equation is equal to the first equation.
*April 11, 2015*

**math - hw help. plz**

To do substitution, choose one of the equations. Then choose a variable in that equation, and express it in terms of the other variable. Finally, substitute it to the other equation. Here, let's choose the 2nd equation. 2x - y = -4/3 Then let's choose the variable y. ...
*April 10, 2015*

**Science**

Use this formula and plug in the given values: F = m * a where F = force (N) m = mass (kg) a = acceleration (m/s^2)
*April 10, 2015*

**Math**

What's the question? Anyway, 35 = 18 cannot be.
*April 10, 2015*

**Math**

The problem asks which of the following covers SOME of the solution for the inequality x ≥ 3. The answers are A, C and D. In letter A, x > 3. They share almost all solutions, but it excludes the number 3. In letter B, x < 0. Definitely they don't share any ...
*April 10, 2015*

**8th grade math**

Let x = minutes Company A: f(x) = 25 , for 0 < x ≤ 100 f(x) = 25 + 0.50(x-100) , for x > 100 Company B: f(x) = 50 , for any value of x
*April 9, 2015*

**Chemistry**

Summation of all heat is zero. Q,aluminum + Q,water = 0 The formula for Q is Q = mc(T2-T1) where m = mass (g) c = specific heat capacity (J/g-K) T = temperature (K) Substitute the values. Note that the final Temperature (T2) is the same for both: [mc(T2-T1)],aluminum + [mc(T2-...
*April 9, 2015*

**Math**

Yes, it's B.
*April 9, 2015*

**Algebra**

p+5, 4p+3, 8p-2 If they are in arithmetic sequence, then have a common difference or (4p + 3) - (p + 5) = (8p - 2) - (4p + 3) Solving for p, 4p + 3 - p - 5 = 8p - 2 - 4p - 3 3p - 2 = 4p - 5 3p - 4p = -5 + 2 -p = -3 p = 3 To get the value of each term just substitute the value ...
*April 9, 2015*

**pre - CALCULUS**

I assumed that (1 + tan^2 u)(1 - sin^2 u) = 1 Note that (1 + tan^2 u) = sec^2 u. [pythagorean identity] And that (1 - sin^2 u) = cos^2 u. [pythagorean identity, from cos^2 u + sin^2 u = 1] Thus, ( sec^2 u )( cos^2 u )= 1 Note that sec u = 1 / cos u, (1 / cos u)^2 (cos^2 u) = 1...
*April 9, 2015*

**pre - CALCULUS**

If you mean, Monthly service charge: $8.80 Per therm service charge 1st 25 therms: $0.6686/therm Over 25 therms: $0.85870/therm therefore for the first 25 therms in a month, 8.80 + 0.6686(25) = ? and for 45 therms in a month, 8.80 + 0.6686(25) + 0.85870(45-25) = ? For x therms...
*April 9, 2015*

**Chemistry**

I assumed that 45 mL of NaOH, and that "02 M" is 0.02 M HCl. Write the balanced equation: HCl + NaOH ---> NaCl + H2O Then get the moles of HCl by multiply the volume by the molarity: M = n/V n = V*M n = 30 mL * 0.02 M n = 0.6 mmol HCl Since in the reaction it'...
*April 9, 2015*

**pre - CALCULUS**

cot θ ∙ sec θ = csc θ Note that cot θ = cos θ / sin θ, and sec θ = 1 / cos θ: cos θ / sin θ ∙ 1 / cos θ = csc θ 1 / sin θ = csc θ Note that 1 / sin θ = csc θ. Thus: csc θ = csc θ
*April 9, 2015*

**chemistry**

If the problem asks for the specific heat capacity, then we just use the formula, Q = mc(T2-T1) where Q = heat (J) m = mass (g) c = specific heat capacity (J/g-K) T2 = final temperature (K) T1 = initial temperature (K) Substituting, 1500 = 100 * c * (50 - 20) c = ? Now solve ...
*April 9, 2015*

**math**

n < 20
*April 9, 2015*

**math**

Let n = average capacity Let n + 1 = capacity of E Therefore, their average is (2 + 5 + 3 + 3 + (n + 1))/5 = n Solving for n, (14 + n)/5 = n 14 + n = 5n n - 5n = -14 -4n = -14 n = -14/-4 n = 7/2 n = 3.5 ton n+1 = 4.5 ton (capacity of E) hope this helps~ `u`
*April 9, 2015*

**Precal**

x^2 - y^2 - 2x + 4y - 6 = 0 First, rearrange the terms as such: x^2 - 2x - y^2 + 4y = 6 We can put parenthesis to separate all terms with x from all terms with y. (x^2 - 2x) + (-y^2 + 4y) = 6 Notice that the coefficient of y^2 is negative. We can factor out -1 so we'll ...
*April 8, 2015*

**chemistry**

We have to look first for the specific heat capacity and latent heat of vaporization for water. These values can be found in textbooks or in google. Specific heat of water, c = 4.18 J/g-K Latent heat of vaporization, Hv = 2256 J/g The first process is heating of the water from...
*April 7, 2015*

**Trigonometry**

Diameter = 24 in Radius = 12 in (a) angular speed (ω) = ? We use the formula: v = ω r Substituting, 15 mi/hr = ω * 12 in Note that 1 mile = 63360 inches, and 1 hour = 60 min: 15 mi * (63360 in / mi) / (1 hr * 60 min / hr) = ω * 12 in 15840 in / min = ω...
*April 7, 2015*

**math**

Perimeter of square: P = 4s where s = side length. Solve for P of square: P = 4 * 6.75 P = 27 It was said that the P of rectangle is 35.54 inches longer than P of square. Thus, P (rectangle) = 27 + 35.54 P (rectangle) = 62.54 round off to nearest tenth: = 62.5 in
*April 7, 2015*

**Physics!**

Formula for power given the current and voltage: P = IV Substituting, P = 5.0 * 120 P = 600 Watts Note that Watts is also Joules / second. Thus to get the energy, we multiply the power by the time: P = E/t E = Pt E = 600 J/s * 42 s E = 25200 J hope this helps~ `u`
*April 7, 2015*

**Math**

Numbers greater than or equal o 3: 3, 4, 5, 6 So, yes it's 4/6.
*April 7, 2015*

**math**

(4n-1)^2 = 16 Get the squareroot of both sides: 4n - 1 = +/- 4 (+): 4n - 1 = 4 4n = 5 n = 5/4 (-): 4n - 1 = -4 4n = -4 + 1 n = -3/4 hope this helps~ `u`
*April 7, 2015*

**cheminstry**

Assuming ideal gas, we can use Charles Law: V1 / T1 = V2 / T2 where V = volume T = absolute temperature (K) It's just direct substitution. I'll do (a): V1 / T1 = V2 / T2 2.5 / 300 = 5 / T2 Solve for the new temperature (T2): 2.5(T2) = 300(5) T2 = 1500 / 2.5 T2 = 600 K ...
*April 7, 2015*

**Math**

Yes, it's B.
*April 7, 2015*

**Chemistry**

Sodium...? Sodium what? Anyway, I'll just provide steps: (1) Write the balanced chemical reaction. Actually I'm not sure with the reaction of this, because of the 'sodium'. Normally it would be Sodium Hydroxide, Sodium Chloride solution, etc. (2) Calculate the ...
*April 7, 2015*

**math**

Divide and simplify them: 2 inch / 20 feet 1 inch / 10 feet Scale is 1 inch = 10 feet
*April 7, 2015*

**Science**

Resistance is 4.0 Alpha...? I think you mean 4.0 Ohms (Ohm has symbol of capital letter of Omega, Ω). Alpha (α) is different, it is the temperature coefficient of resistance. Anyway, you use the formula: I = V/R where I = current (Ampere) V = voltage (Volts) R = ...
*April 7, 2015*

**calculus**

First, we get the boundaries of the arch. The boundaries of the arch has y-coordinate of zero (when it crosses the x-axis), thus, 0 = cos(x/4) cos^-1 (0) = x/4 π/2 = x/4 x = 2π -π/2 = x/4 x = -2π Thus, boundary is from -2π to 2π. Actually, there ...
*April 7, 2015*

**Math**

The problem says that he increases the distance he runs by 15%, not by 15 miles. First, we get how much distance is increased in the first week, by getting the 15% of the original distance he can cover: 15% of 8.5 can be translated mathematically to 0.15 x 8.5 which is equal ...
*April 7, 2015*

**math**

Well, you use substitution. To do substitution, you choose one of the equations, and express one of the variables in terms of the other. Actually, here, we can see that the first equation (3a = 6-b) can be readily substituted to the second equation (3a = 4-b), because of they ...
*April 7, 2015*

**ALGEBRA /116**

-5x/7 - 2 > -1 Solve for x like a normal equation: -5x/7 > -1 + 2 -5x/7 > 1 -5x > 7 -x > 7/5 Now, when you multiply both sides by a negative number (in this case, it's -1), the inequality sign changes to opposite: x < -7/5 x < -1.4 Or if that's not...
*April 7, 2015*

**algebra/116**

Plug in the value of x and y of each point in the equation of the line. If it satisfies, then that point is a solution or is located on the line. For instance, take (0,-6). In this point, x = 0 and y = -6. If you substitute x = 0 to the equation, you should get a value of y...
*April 7, 2015*

**algebra**

Note that x^-2 = 1/x^2 Therefore, (x^-3 + y^-1) / x^-2 = (1/x^3 + 1/y) / 1/x^2 = (x^2)(1/x^3 + 1/y) = (x^2 / x^3) + (x^2 / y) = 1/x + x^2/y
*April 7, 2015*

**math**

Let x = original price. The given amount is already the discounted price, therefore: original price - (13% of original price) = 870000 or x - (0.13x) = 870000 0.87x = 870000 x = 870000/0.87 x = ?
*April 7, 2015*

**math**

(a) Ratio and proportion: 4 gray : 5 blue = 60 gray : x blue To solve for n, we can rewrite it in fraction: 4/5 = 60/x Cross-multiply: 4x = 60*5 4x = 300 x = 300/4 x = 75 blue tiles (b) Let n = some factor since their ratio (4:5) is always the same, we can say that 4n + 5n = ...
*April 7, 2015*

**Chemistry**

Hmm, is that really capital letter 'M' (Molarity) or small letter 'm' (molality)? Anyway, I'll just assume it's Molarity. First, we get the molar mass of KBr. You'll need a periodic table to to solve for it. Anyway, KBr has molar mass of 119 g/mol. ...
*April 6, 2015*

**Physics**

Momentum formula: momentum = mass x velocity substituting, 20 = 12 * v v = ? Units in m/s
*April 6, 2015*

**Algebra 1**

y= -x^2 + 1/2x + 2 There are plenty of ways to get its maximum/minimum. One way is to graph and locate on the graph the point where max/min occurs. Another is to solve for its vertex. We can transform the equation into the form y = a(x-h)^2 + k where (h,k) is the vertex. ...
*April 6, 2015*

**Physics**

The object experiences uniformly accelerated motion (UAM) so we can use the formula: vf^2 - vo^2 = 2gd where vf = final velocity vo = initial velocity g = acceleration due to gravity = 9.8 m/s^2 d = distance Since the object is in free fall, vo is zero: vf^2 - 0 = 2*9.8*3 vf^2...
*April 6, 2015*

**Physics**

Since the camera experiences uniformly accelerated motion (UAM), we can use the formula h = vo*t - (1/2)gt^2 where vo = initial velocity (m/s) h = height (m) t = time (s) g = acceleration due to gravity = 9.8 m/s^2 Since the camera is in free fall (it was dropped right before ...
*April 5, 2015*

**Math**

No it isn't A. First, we get the total or sum of the four test scores by multiplying the mean by 4: 85 * 4 = 340 Then, we subtract this by the sum of the other three given test scores to find the fourth: 340 - (81 + 83 + 85) = ? hope this helps~ `u`
*April 5, 2015*

**physics**

v = ω * r where v = linear/tangential velocity (m/s) ω = angular velocity (rad/s) r = radius (m) Since the wheels rotate at 1 rev/s (this is the angular velocity), its equivalent to rad units is 2π rad/s. And since the wheels have circumference of 2 m, the ...
*April 5, 2015*

**chemistry**

Because if you plot the second derivative, (that is, (Δ(ΔpH/ΔV)/ΔV) versus Volume), you'll see that the equivalence point corresponds to the volume where the graph crosses the x-axis (or at (Δ(ΔpH/ΔV)/ΔV) = 0). From there you can ...
*April 5, 2015*

**Physics**

First, we solve for the mass of the person. Because mass of any object is not changing or constant. We use the formula for weight: W = mg where W = weight (N) m = mass (kg) g = acceleration due to gravity = 9.8 m/s^2 substituting, 500 = m*(9.8) m = 500/9.8 m = 51.02 kg Since g...
*April 5, 2015*

**Calculus**

No need for trig substitution. We'll just do normal substitution: Let u = sqrt(x^2 - 4) Thus, we can make the following relation: u^2 = x^2 - 4 x^2 = u^2 + 4 2u du = 2x dx dx = u/x du Substituting, ∫ ( x^3 * sqrt(x^2-4) ) dx ∫ ( x^3 * u * u / x ) du ∫ ( x...
*April 5, 2015*

**PHYSICS HELP!!**

In projectile motion, we can use the formula, d = vo,x * t or d = vo cos(a) * t where d = distance traveled horizontally vo = initial velocity vo,x = initial horizontal velocity a = angle t = time Substituting, 15 = vo * cos(38) * 1.30 vo = ? hope this helps~ `u`
*April 5, 2015*

**Science**

Work is force multiplied by distance, or W = F*d Substitute the given values: W = 50 N * 5 m W = ? Units in Joules. Hope this helps~ `u`
*April 4, 2015*

**Elementary Algebra**

Note that rate is distance traveled over time, or r = d/t If you have walked 1 mile from 6:00 to 7:30 (that's 1.5 hours, right?), then your average rate is r = 1 mile / 1.5 hours r = 2/3 mph This is your average rate. And we assume this as constant. If we make a linear ...
*April 4, 2015*

**Differential Equation**

Sorry I forgot to put the constant from integration. Thus, F = e^xy + x + 2y + C
*April 4, 2015*

**Differential Equation**

(ye^xy + 1)dx + (xe^xy + 2)dy = 0 Check for exactness: Let M = ye^xy + 1 Let N = xe^xy + 2 ∂M / ∂y = ∂N / ∂x ∂(ye^xy + 1) / ∂y = ∂(xe^xy + 2) / ∂x Use chain rule to get the derivative: e^xy + xy e^xy = e^xy + xy e^xy Thus it is ...
*April 4, 2015*

**News**

Tingin ko mahirap sya ipredict kasi walang signal na magsasabi na parating na yung lindol, or something, unlike sa mga weather forecasts na kayang ipredict exactly yung time and location kung saan tatama yung bagyo, typhoon, etc. and yung lakas nito (kaya may idea tayo kung ...
*April 4, 2015*

**math**

Let x = salary Let (x-3000)/5 = cost of shoes Therefore, total salary minus his costs is the 2/5 of his salary left: x - 3000 - (x-3000)/5 = (2/5)x [ x - 3000 - (x-3000)/5 = (2/5)x ] * 5 5x - 15000 - x + 3000 = 2x 2x - 12000 = 0 2x = 12000 x = 6000 hope this helps~ `u`
*April 2, 2015*

**math**

Let x = Daisy stickers Let y = Henry stickers According to the problem: (1/4)y = (2/3)x And understanding the first statement, we can say that Henry has more stickers than Daisy: y - x = 135 Substituting the second equation to first (with y = 135 + x); (1/4)(135 + x) = (2/3)x...
*April 2, 2015*

**physics**

Assuming the air is ideal, you can use the formula P1 * V1 / T1 = P2 * V2 / T2 where P1 and P2 = initial and final pressures respectively (psi) V1 and V2 = initial and final volumes respectively (ft^3) T1 and T2 = initial and final absolute temperatures respectively (Rankine)
*April 2, 2015*

**Chemistry**

Note that the molar mass of H2O is 18 g/mol. If you're not sure how to calculate for the molar mass, get a periodic table and look for the individual masses of the elements present in the chemical formula. For instance, in the periodic table, H has mass of 1 g O has mass ...
*April 1, 2015*

**algebra**

The equation for this relationship is a linear equation (I even used linear regression to prove it lol). To get the linear equation, we can look for the slope first. m = (y2 - y1) / (x2 - x1) where (x1,y1) and (x2,y2) are points on the line. Taking two points, for instance, (0...
*April 1, 2015*

**math**

Let x = the number of problems where he got it right since the total number of problems is 12, Let 12-x = the number of problems where he git it wrong Now, it was said that 5 points are awarded for every correct answer, or 5x and 2 points are deducted for every wrong answer, ...
*March 31, 2015*

**Math**

First we get the percentage of the students who liked the program: (218 / 245) * 100 = 88.9796 % Recall that a circle has a measure of 360 degrees. 360 degrees corresponds to the whole. Since 88.9796 % of the whole is the percentage of students who liked the program, 360 ...
*March 31, 2015*

**Algebra 2**

y = (x-5) / (x^2 - 6x + 5) Simplifying, y = (x-5) / (x - 5)(x - 1) y = 1 / (x-1) The root of the denominator is discontinuity: x = 1 : an asymptotic discontinuity The other roots (before simplification) is also a discontinuity: x = 5 : a removable discontinuity If you plot ...
*March 31, 2015*

**Chemistry**

C2H4 + O2 ---> CO2 + H2O Balancing, it becomes C2H4 + 3O2 ---> 2CO2 + 2H2O
*March 31, 2015*

**Chem**

Note that the process involved here is the phase change of ice, from solid (ice) to liquid (water). Thus, the heat involved is latent heat, not sensible heat. The latent heat of fusion of ice is approximately 334 J/g. You can look for this value in textbooks or google. Then we...
*March 31, 2015*

**physics**

We use the formula PE = mgh where PE = potential energy (J) m = mass (kg) g = acceleration due to gravity = 9.8 m/s^2 h = height (m) Substituting, 1970 = 82(9.8)(h) h = 2.45 m hope this helps~ `u`
*March 30, 2015*

**Physical science**

If v is velocity, d is distance, and t is time, therefore we can use the formula v = d/t Substituting, 55 = 68 / t t = 68 / 55 t = 1.236 hours hope this helps? `u`
*March 29, 2015*

**Chemistry**

Molality units is moles of solute per kilogram solvent. In this case, we have m = 4 moles urea / 1000 g H2O Note that water has molar mass of 18 g/mol. Getting the moles of water, we need to divide the given mass by its molar mass: 1000 g H2O / 18 g/mol = 55.56 mol H2O Since ...
*March 29, 2015*