Wednesday

February 10, 2016
Total # Posts: 1,926

**math**

Note that the equation is in slope-intercept form, y=mx+b where m is the slope and b is the y-intercept In the equation y=-1/3x + 3, therefore the slope is -1/3.
*March 16, 2015*

**Algebra**

To get the x-intercept, let y = 0 and solve for x: -3x + 4y = -12 -3x + 4(0) = -12 -3x = -12 x = 4 Thus x-intercept is at (4,0) To get the y-intercept, let x = 0 and solve for y: -3x + 4y = -12 -3(0) + 4y = -12 4y = -12 y = -3 Thus y-intercept is at (0,-3) hope this helps~ `u`
*March 16, 2015*

**Maths**

Average weight is the total weight divided by the number of people. To find the average weight of boys, we first look for the total weight of all (boys + girls), and the total weight of the girls. Weight of all (boys + girls): 44 * 50 = 2200 kg Weight of girls: 40 * (50 - 40) ...
*March 15, 2015*

**Calculus**

Substitute y = 3x - 7 to x^2*y: x^2 * (3x - 7) 3x^3 - 7x^2 Then differentiate with respect to x, and equate to zero (since we're looking for maximum/minimum): 9x^2 - 14x = 0 x(9x - 14) = 0 x = 0 x = 14/9 Note that if x = 0, the minimum product of x^2 * y is zero. But if x...
*March 15, 2015*

**Calculus**

*Correction* I'm sorry, the one I did is not called L'hopital's rule. That is just another technique of finding limits (dividing numerator and denominator by the variable with highest degree). L'hopital's rule is different, for it uses separate ...
*March 15, 2015*

**Calculus**

lim [ 6x^2 / (200-4x-kx^2) ] as x->infinity = 1/2 Notice that the numerator and denominator has the same highest degree of x. Therefore, we can use the L'hopital's rule. To do this, we divide both numerator and denominator by x^2: lim [ (6x^2 / x^2) / (200-4x-kx^2)/...
*March 15, 2015*

**Algebra**

(1) Yes (2) Yes (3) Hmm how did you arrive with your answer, because I'm getting, = 70 + 40 + 2(30 + .29) = 110 + 2(30.29) = 110 + 60.58 = 170.58 or perhaps there is typo or missing info? And I'm also curious with your use of 'm' units.
*March 15, 2015*

**Physics**

P,abs = P + pgh P = (1.01*10^5 Pa) + (1025 kg/m^3)*(9.8 m/s^2)(15 m) P = 101000 + 150675 P = 251675 Pa Check the significant figures. Hope this helps~ `u`
*March 14, 2015*

**Calc**

∫ (2x+1)/(x+1) dx We can separate this term into two terms by taking each term in the numerator: ∫ (2x)/(x+1) + 1/(x+1) dx For the term on the right, ∫ 1/(x+1) dx = ln |x+1| For the term on the left, Let u = x+1, thus x = u-1, and dx = du Replacing, 2 ∫...
*March 14, 2015*

**Calculus check**

Yes, that's right. `u`
*March 14, 2015*

**maths**

To get the lateral surface area, simply multiply the base perimeter by the height, 25 cm * 40 cm = ? hope this helps~ `u`
*March 14, 2015*

**chemistry**

First, we write the balanced reaction: 2 AgNO3 + K2S -> 2 KNO3 + Ag2S Recall that molarity is moles per liter solution, or M = n/V Then we get the number of moles of K2S by simply multiplying the volume (should be in L units) by the concentration (Molarity has units mol/L...
*March 13, 2015*

**Math**

(1) You have to recall some laws of exponents. 15 * 3^(y+1) - 243 * 5^(y-2) = 0 3 * 5 * 3^(y+1) - 3^5 * 5^(y-2) = 0 5 * 3^(y+1+1) - 3^5 * 5^(y-2) = 0 5 * 3^(y+2) = 3^5 * 5^(y-2) 3^(y+2) / 3^5 = 5^(y-2) / 5 3^(y+2-5) = 5^(y-2-1) 3^(y-3) = 5^(y-3) The only number that will ...
*March 13, 2015*

**Math Functions (if i have correct answer)**

Max height - yes, we got approximately the same answer Time - the time you got is the time where the ball reached the maximum height. The question asks for the total time (the time the ball is above the surface of Mercury), therefore you should multiply it by 2, so it would ...
*March 13, 2015*

**math**

f varies inversely with g: f = k * (1/g) where k is some constant. f=20 when g=4: 20 = k * (1/4) k = 20 * 4 k = 80 f=? when g=10 f = 80 * (1/10) f = 8 Hope this helps~ `u`
*March 12, 2015*

**Algebra**

an = ao + (n-1)d where an = the nth term ao = the first term n = number of terms d = difference between two consecutive terms Substituting the given, (i) a6 = 13 (here, n=6, an=13) 13 = ao + (6-1)d 13 = ao + 5d (ii) a10 = 25 (here, n=10, an=25) 25 = ao + (10-1)d 25 = ao + 9d ...
*March 12, 2015*

**chemistry**

We write the reaction: HC2H3O2 + KOH -> KC2H3O2 + H2O The products are potassium acetate (salt) and water.
*March 12, 2015*

**chemistry**

Assuming the gas is ideal, for a fixed volume of gas, we can use the Gay-Lussac Law, which states that Pressure is directly proportional to Temperature of gas: P = kT where P = pressure k = some constant T = temperature (in Kelvin) If we're given sets of values for ...
*March 12, 2015*

**math**

Recall that speed is distance traveled over time: v = d / t Rearranging to get t, t = d / v For the two trips, the distance traveled is the same, while the speed and time of travel are different. We represent each time traveled as such: Let t1 = time traveled (towards Rocky ...
*March 12, 2015*

**Separation processes**

If the "low" volatility in the question means it is CLOSE to 1 (not equal to 1), then the answer is letter 'D' or 'separation of components is difficult. If it said "exactly equal to 1", then it's 'B'. But since it doesn't ...
*March 12, 2015*

**help**

Because half-life means final amount becomes 50% of original, therefore, after another half-life time, the final amount becomes 25% of original. Well if you look at the problem, all you have to do is multiply the the half-life 12.3 years by 2, which is 24.6 years. But if you ...
*March 11, 2015*

**Math**

Represent the unknowns. Let x = length since the width is 3/4 of the length, Let (3/4)x = width Recall that the area of rectangle is just width multiplied by the length, A = w * l Substituting, 432 = (3/4)x * x 432 = (3/4)x^2 432 * 4/3 = x^2 576 = x^2 Get the square root of ...
*March 11, 2015*

**Chemistry help please**

Yes, that's right. The oxidation number of P in P2O3 is +3.
*March 11, 2015*

**Math**

This problem looks similar to the other math problem posted here. OwO Anyway, first represent the unknowns. Let x = length since the width is 2/3 of the length, Let (2/3)x = width Recall that the area of rectangle is just width multiplied by the length, A = w * l Substituting...
*March 11, 2015*

**Chemistry ( I NEED HELP, PLEASE!!!, IM DESPERATE!)**

First, we balance the chemical reaction: 2 Na2O2 + 2 H2O → 4 NaOH + O2 Then, we need to determine the molar masses of Na2O2 and O2 in order to convert them to moles. To get them, we need the mass of each element in the formula and add. In the periodic table, Na = 23 and ...
*March 11, 2015*

**algebra**

Note that an object falling freely experiences uniformly accelerated motion (UAM). In this case, we can use the formula, h = vo * t - (1/2) * g * t^2 where h = height or distance vo = initial velocity t = time g = acceleration due to gravity = 9.8 m/s^2 = 32.2 ft/s^2 Since the...
*March 11, 2015*

**english**

setting
*February 11, 2015*

**Adverbs **

Which words make up the adverb phrase in this sentence? The school bus crosses two bridges along its route. A. along its route B. two bridges along C. The school bus D. crosses two bridges
*November 25, 2014*

**grovment**

General public might be swayed by a charismatic leader.
*November 25, 2014*

**intermediate math**

Recall that distance is equal to rate (or speed) mutiplied by time: d = v*t Let r = speed of Payton Let r + 4.5 = speed of Angie If they are jogging opposite to each other, then the distance between them is equal to the sum of their rates multiplied by the time: d = r*t + (r+4...
*September 29, 2014*

**chemistry**

Recall Boyle's Law: P1 * V1 = P2 * V2 where P1 = initial pressure P2 = final pressure V1 = inital volume V2 = final volume This is applicable if Temperature is held constant. Substitute the given values and solve for P2. Hope this helps~ :)
*September 28, 2014*

**Chemistry- colligative properties**

Van't Hoff factor can be associated to the property of the substance (if it's strong electrolyte, weak electrolyte, etc.), and can be approximated by counting the number of ions dissociated in water. a. i ~ 1 (weak acid, therefore weak electrolyte) b. i = 2 (strong ...
*September 28, 2014*

**Physics**

Formulas we need (uniformly accelerated motion): h = vo*t - (1/2)gt^2 vf^2 - vo^2 = 2gd Let H,t be the height of tower. The first stone thrown upward reaches its maximum height, h,max = vo^2 / 2g h,max = 15^2 / 19.6 h,max = 11.4796 meters (above the tower) and the time needed ...
*September 28, 2014*

**mathematics**

A bag contains 10 red, 15 white, 25 green balls. What should be the minimum number of balls drawn without replacement so that you get 5 red, 3 white, 10 green balls.
*September 9, 2014*

**college algebra**

A large rectangular movie screen in an IMAX theater has an area of 7200 square feet. Find the dimensions of the screen if it is 10 feet longer than the width.
*September 6, 2014*

**Calculus**

f(x)=sqrt(x^3+2) We can also rewrite this as, f(x) = (x^3 + 2)^(1/2) Then we can use chain rule, f'(x) = (1/2)*(3x^2)*(x^3 + 2)^(-1/2) Finally, the second derivative is f''(x) = (3/2)(2x)(x^3 + 2)^(-1/2) + (3/2)(x^2)(3x^2)(-1/2)(x^3 + 2)^(-3/2) And simplify. Hope ...
*May 16, 2014*

**geometry**

Recall the Pythagorean theorem: c^2 = a^2 + b^2 where c is the hypotenuse (which is also the longest side of a right triangle) and a & b are the legs. Substitute each side lengths to the equation. Of course the longest side is c, and the remaining sides are a and b. If the set...
*May 16, 2014*

**phys**

A boat is traveling upstream at 14 mph with respect to a river that is flowing at 6 mph (with respect to the ground). A man runs directly across the boat, from one side to the other, at 6 mph (with respect to the boat). The speed of the man with respect to the ground is:
*February 19, 2014*

**Math - Check my answer?**

Yes that's correct.
*January 8, 2014*

**Math check**

1. Actually it's B. Expanding, 2(x - 3) = 2x 2x - 6 = 2x -6 = 0 Note that if you get an answer like this (constant = zero), there is no solution. 2. It's D. (btw I don't know why you put question mark beside 3) Expanding, 3(y - 3) = 2y - 9 + y 3y - 9 = 3y - 9 or 0...
*January 8, 2014*

**algebra**

Let A = number of sweets of Alvin Let C = number of sweets of Calvin Let M = number of sweets of Melvin According to the statements, A < C A + C = 31 M = A + 24 Note that to maximize M, A should also be maximized. Maximum value of A is 31 (that is, if C = 0), but according ...
*December 30, 2013*

**geometry**

Recall that surface area of cone is SA = pi*r^2 + pi*r*s where r = radius s = slant height Substituting, SA = 3.14 * 15^2 + 3.14 * 15 * 11 SA = 706.5 + 518.1 SA = 1224.6 sq units Hope this helps :3
*December 29, 2013*

**MATHS**

Area of disc (circle): A = pi*r^2 A = 3.14 * 7^2 A = 153.86 cm^2 Area of cardboard (rectangle): A = L * W A = 70 * 50 A = 3500 cm^2 Divide area of rectangle by area of circle: 3500 / 153.86 = 22.75 Take only the whole number: 22 discs Hope this helps :3
*December 29, 2013*

**Genius Math**

Hmm, the triangle seems impossible, because if you draw it, given the condition that AC = BC (thus it's an isosceles triangle), then angle ACB = 96, therefore BAC = 96 degrees also (since the sides opposite to the angles are equal). So if there are two angles which are 96...
*December 24, 2013*

**Chemistry**

When naming alkanes, alkenes, alkynes, yes, it's the longest chain that is first counted. And then identify the groups attached to to. (For instance methyl, ethyl, etc). Then number the carbon in the longest chain, starting from the nearest attached group (if it's ...
*December 21, 2013*

**Mechanics**

Recall that Pressure is just Force over a unit Area, or P = F/A We are given the force (which is 220 N), therefore, we only need to find area. A = L*W A = 4*3 = 12 m Therefore, P = 220 / 12 P = 18.33 N/m^2 P = 18.33 Pa Hope this helps :3
*December 21, 2013*

**math**

Find the value of df^-1/dx at x=f(a). f(x)=5x+8, a=-1 i got 5?
*December 19, 2013*

**science**

That's correct. :)
*December 18, 2013*

**Algebra 1**

Let x = weight of chicken in pounds Let y = total cost of x pounds of chicken Therefore, y = 2.99x To see the graph of this, go to wolframalpha . com and type in the equation. Hope this helps :3wol
*December 18, 2013*

**math**

f(x) = 7x - 2
*December 18, 2013*

**algebra**

Substitute T = 141 to the equation: 141 = –0.005x^2 + 0.45x + 125 Simplify: –0.005x^2 + 0.45x + 125 - 141 = 0 –0.005x^2 + 0.45x - 16 = 0 Recall that discriminant is just D = b^2 - 4ac if D < 0 : imaginary root D = 0 : real, equal root D > 0 : two real, ...
*December 18, 2013*

**Pre-Calculus**

*I mean you get all the factors of x = +/- p/q. In the problem, x = +/- 20, and its factors are written there above. The factors are the ones you have to check by substituting them to the expression. :)
*December 16, 2013*

**Pre-Calculus**

You use rational root theorem. Let p = constant term Let q = numerical coefficient of highest degree of x x = +/- p/q In here, p = -20 and q = 1. Thus, x = (+/-) 1 , 2 , 4 , 5 , 10, 20 You have to substitute each factor (for instance x = -1) to the expression, and if you get a...
*December 16, 2013*

**Math Quick Question**

You spoke to that person for 45 minutes only.
*December 8, 2013*

**Chemistry(DrBob222)**

Yes, that's right. :)
*December 8, 2013*

**math**

1/13 = 0.0769230769230... The repeating numbers are 076923 (six numbers), thus, 43 / 6 = 7 remainder 1. Therefore counting from zero, the 43rd digit after the decimal point is 0. hope this helps. :3
*December 7, 2013*

**Math**

1. No 2. Parallel
*December 7, 2013*

**Math**

x + 7 ≥ 3x x - 3x ≥ -7 -2x ≥ -7 x ≤ 7/2 x ≤ 3.5 3x + 4 ≤ 5x 3x - 5x ≤ -4 -2x ≤ -4 x ≥ 2 Therefore, the common solution is from 2 to 3.5, or 2 ≤ x ≤ 3.5 Hope this helps :3
*December 7, 2013*

**algebra**

d = 0.05r^2 + r Substitute r = 45: d = 0.05(45)^2 + 45 d = 101.25 + 45 d = 146.25 ft To the nearest foot, d = 146 ft Hope this helps :3
*December 7, 2013*

**math**

h(n) = 100 / 9 n Substitute n = 27: h(27) = (100 / 9) * 27 h(27) = 100 * 3 h(27) = 300 dollars hope this helps :3
*December 7, 2013*

**math**

12 - q ≥ -13 Just solve it like a true equation: 12 + 13 ≥ q 25 ≥ q or q ≤ 25 Hope this helps :3
*December 7, 2013*

**Chemistry**

Formula to be used: Molality = moles of solute / kg solvent Steps: #1. To do this, get the molar mass of Tin, using a periodic table. Fomula for Tin in Sn (look it up in the periodic table, and you'll see its mass). #2. After you get the mass of Tin, divide it by 5 g, and ...
*December 4, 2013*

**Chemistry**

*repost* Formula for osmotic pressure: Π = MRT * i where m = molarity (mol solute / L solution) R = universal gas constant = 0.0821 L-atm/mol-K T = temperature (K) i = van't Hoff factor (approximately equal to ionizable ions) Note that sucrose is soluble in water, but...
*December 4, 2013*

**Chemistry**

Formula for osmotic pressure: Π = MRT * i where m = molarity (mol solute / L solution) R = universal gas constant = 0.0821 L-atm/mol-K T = temperature (K) i = van't Hoff factor (approximately equal to ionizable ions) Note that sucrose is soluble in water, but does not...
*December 4, 2013*

**Algebra 1**

Yes, your answer is correct. :) (I thought at first the radius is 2 and 1/2, not 21/2, but I guess that's too small) :3
*December 4, 2013*

**Geometry**

Use Heron's formula. Let a, b and c be the sides of a triangle. Let s = a + b + c Therefore the area of triangle can be calculated using this formula: A = sqrt[ (s)(s-a)(s-b)(s-c) ] It should be a little easy using this formula, so I guess you can do it on your own. :) ...
*December 4, 2013*

**Calculus**

limit (sin(4x+12))/(5x+15) as x -> -3 If we try substituting, = (sin(4(-3)+12))/(5(-3)+15) = sin(-12+12) / -15+15 = sin(0) / 0 = 0 /0 Note that 0/0 is indeterminate, and if you arrive at this answer, you use the L'hopital's rule. To use the L'hopital's rule...
*December 2, 2013*

**Physics**

You can use the formula for Uniformly Accelerated Motion (UAM): h = (v,o)t - (1/2)gt^2 Or you can use another formula, which does not use time: v,f^2 - v,o^2 = 2gd where v,f = final velocity v,o = initial velocity g = acceleration due to gravity = 9.8 m/s^2 d = distance (in ...
*December 1, 2013*

**math**

1. Yep 2. The remaining distance is is 120 - 60 = 60 miles (because the first 60 miles was already covered in 1.2 hours according to #1) Speed is distance over time, or v = d/t Substituting, 40 = 60/t t = 60/40 t = 1.5 hours 3. Yep
*December 1, 2013*

**math**

Let x = multiplier. Thus, Men = 7x Women = 5x The ratio of men to women is still 7 to 5. Since there are 440 more men than women, we can say that 7x = 5x + 440 Solving for x, 7x - 5x = 440 2x = 440 x = 220 The total men and women is 7x + 5x = 12x. Thus the total is, total = ...
*December 1, 2013*

**Physics**

Steps: 1. Get the volume of the sphere (baseball). You re given the diameter, and you can get the radius by dividing this by 2. You are also given the formula: V,sphere = 4/3 * π * r^3 Just substitute the value of radius to get V. 2. Divide the given mass by volume to get...
*December 1, 2013*

**Physics**

If you use the equation for heat released/absorbed to support your explanation, Q = m*c*(T2 - T1) where m is the mass, c is the specific heat capacity and T is the temperature. Since the only substance involved is water, c is the same for both systems. We can also say that the...
*December 1, 2013*

**Physics**

Because ice can absorb more heat from the soft drink to change its state from ice to water (latent heat), than water only. If you use the equation for heat released/absorbed, Let T2 = final temperature of ice (assume it's above 0°C, so it became water at some temp >...
*December 1, 2013*

**Math**

y = (1/2)x^2 - (3/2) -> this is a parabola differentiate: dy/dx = (1/2)*2*x - 0 dy/dx = x The line 4x - 8y = 5 has a slope of, -8y = -4x + 5 y = (1/2)x - 5/8 slope = 1/2 If this line and the tangent line of the parabola are parallel, they have the same slope: dy/dx = x 1/2...
*December 1, 2013*

**Physics**

Because it absorbs heat change its state from liquid to gas. This is called the latent heat, and it is a constant-temperature process. If the temperature changes without changing the state of a substance, it is called sensible heat. Hope this helps :3
*December 1, 2013*

**Math**

2a^2 b^3 (4a^2 + 3ab -ab) Distribute to each: 2a^2 b^3 * 4a^2 = 8a^4 b^3 2a^2 b^3 * 3ab = 6a^3 b^4 2a^2 b^3 * (-ab) = -2a^3 b^4 Adding them, 8a^4 b^3 + 6a^3 b^4 -2a^3 b^4 = 8a^4 b^3 + 4a^3 b^4 Actually either there's no answer in the choices, or there is a typo. :3
*December 1, 2013*

**algebra 1**

Um, I think I answered the same question before.. but probably I didn't explain it clearly. :3 First thing we know is that the boiling temperature of water is dependent on the altitude. We can let x as the altitude (independent variable) and y as the boiling temp (...
*December 1, 2013*

**Math**

Yes. :) The equation containing (2,4) with slope equal to -2 is y = -2x + 8.
*December 1, 2013*

**Math**

Is this the continuation of your question? :) In the previous question, we know the slope is -2, and therefore we use the point-slope formula to get the equation: y - y1 = m(x - x1) We only need the slope and one point to get the equation. Let's use the point(2,4). ...
*December 1, 2013*

**PreCal**

^No, I'm sorry don't mind my post ^^;
*December 1, 2013*

**PreCal**

2yi = 5x - 2i + 4 Divide everything by 2i to get y alone: 2yi / 21 = (5x - 2i + 4) / 2i y = (5/2i)x - 1 + 2/i Hm, I think there's a typo..
*December 1, 2013*

**Math**

There are actually infinite number of possible point B here, because if point A and point B lie on a line with a slope of -2, then two different points on that line have can be connected with a line of slope equal to -2. (I hope that's clear ^^;) But just to show how to ...
*December 1, 2013*

**Math**

1. Yep 2. Yep 3. Yep 4. Yep 5. Yep 6. Yep 7. Yep 8. Yep
*December 1, 2013*

**MATH**

Gemma: the first and second ordered pairs Tessa: the third and fourth ordered pairs I think you can observe them easily. hope this helps :3
*December 1, 2013*

**MATH :)**

They are all correct, except #5. 1.30 x 10^4 has three significant figures (1,3 and 0). hope this helps :3
*November 30, 2013*

**Chemistry**

Get first the number of moles (n) of each species. To get the moles, divide the mass by the molar mass. To get the molar mass, get a periodic table and add the individual mass of the elements in the chemical formula. H2O (water): 2*1 + 1*16 = 18 g/mol C3H8O3 (glycerine): 3*12...
*November 29, 2013*

**Chemistry**

Get first the number of moles (n) of each species. To get the moles, divide the mass by the molar mass. To get the molar mass, get a periodic table and add the individual mass of the elements in the chemical formula. H2O (water): 2*1 + 1*16 = 18 g/mol C3H8O3 (glycerine): 3*12...
*November 29, 2013*

**Math**

64 x 6^4 = 2^6 * 2^4 * 3^4 = 2^10 * 3^4 = 82944
*November 27, 2013*

**math**

Let n = number of laptops sold 5 / 9 = 20 / n 5n = 9 * 20 5n = 180 n = 36 laptops
*November 27, 2013*

**algebra 1**

You can observe that the difference between two consecutive numbers in the pattern is 9.
*November 27, 2013*

**Chemistry**

I think you lack data, and thus, this question cannot be answered.
*November 27, 2013*

**Chemistry**

Molar mass of SO2 = 64 g/mol Divide the given mass by molar mass to get the moles: n = 0.7 / 64 n = ? Now solve for n.
*November 27, 2013*

**Calculus**

Integral of x / sqrt(x-1) dx We can use substitution method. Let u = x - 1 Thus, x = u + 1 and dx = du Substituting, Integral of (u+1)/sqrt(u) du Integral of (u+1)(u^(-1/2)) du Integral of u^(1/2) + u^(-1/2) du = (2/3)*u^(3/2) + (2)*u^(1/2) + C = (2/3)*(x-1)^(3/2) + 2(x-1)^(1/...
*November 27, 2013*

**Algebra**

Just substitute x = -3 to the function: f(x) = 3x - 10 f(-3) = 3(-3) - 10 f(-3) = -9 - 10 f(-3) = -19 Hope this helps :3
*November 25, 2013*

**math**

x = (2/y^2) + 2 Place the 2 from the right side to the left side. x - 2 = 2 / y^2 Multiply both sides by y^2. (x - 2) * y^2 = (2 / y^2) * y^2 (x - 2) * y^2 = 2 Divide 2 from the right side by x - 2 to isolate all terms with y. y^2 = 2 / (x - 2) Finally, get the squareroot. y...
*November 24, 2013*

**math**

Let n = total number of students. It was said that 60% of n are girls, which is according to the problem, equal to 30. Thus, 60% * n = 30 Note that 60% is also equal to 0.6 in decimal form: 0.6 * n = 30 n = 30/0.6 n = 50 students Hope this helps :3
*November 24, 2013*

**Chemistry**

To do this, you need the the latent heat of vaporization (Lv) for water. In references, the Lv for water is 2256 J/g. The formula for the heat released of absorbed is Q = m * Lv where m = mass Lv = heat of vaporization In this case, heat is released (negative Q) because the ...
*November 24, 2013*

**Chemistry**

To do this, you need the the latent heat of vaporization (Lv) for water. In references, the Lv for water is 2256 J/g. The formula for the heat released of absorbed is Q = m * Lv where m = mass Lv = heat of vaporization In this case, heat is released (negative Q) because the ...
*November 24, 2013*

**Pre-Calc (Prove the identity)**

Recall that formula for sum in tangent: tan (a +/- b) = [tan(a) +/- tan(b)] / [1 -/+ tan(a)tan(b)] Applying this, tan^2(x/2 + π/4) = { [tan(x/2) + tan(π/4)] / [1 - tan(x/2)tan(π/4)] }^2 Note that tan(π/4) = 1, so = [(tan(x/2) + 1) / (1 - tan(x/2))]^2 = (tan...
*November 24, 2013*

**Math grade 9 and up**

x/s + y/w = 1 s/x + w/y = 4 You can use substitution. From the first equation, wx + sy = sw x = (sw - sy)/w Substitute to the second equation: s/x + w/y = 4 sy + wx = 4xy sy + (w)((sw - sy)/w) = 4((sw - sy)/w)y sy + sw - sy = 4y(sw - sy)/w sw^2 = 4swy - 4sy^2 4sy^2 - 4swy + sw...
*November 23, 2013*