Friday

July 3, 2015

July 3, 2015

Total # Posts: 1,869

**Science**

It's the third one, the 10.0m/s[E] since it has direction, which makes it a 'vector' quantity. The other three choices only measure the speed, while 10.0m/s[E] is velocity.
*July 3, 2015*

**Chemistry**

Their outer shell is already full, so they won't react easily. For Helium, that's 2 electrons, while for the rest of noble gases, it's 8 electrons.
*July 3, 2015*

**MATH**

The answer is yes for both questions.
*July 3, 2015*

**algebra**

Well this is just direct substitution of the given values. I'll do #1 and #2, and you do the rest: #1. apx + 1 = ? Since it was given that a = -10, p = -1 and x = 6, substituting, (-10)(-1)(6) + 1 = ? 60 + 1 = 61 #2. ry - c = ? Since it was given that c = -2, r = 3, and y...
*July 3, 2015*

**Chemistry**

Moles is given mass divided by the molar weight, or n = m / MW Substituting, n = 0.50 / 4 n = 0.125 mol He
*July 3, 2015*

**calculus**

A = Ao*e(^0.000124t) If the final amount, A, is equal to 10% of initial amount, Ao, thus 0.1*Ao = Ao*e(^0.000124t) 0.1 = e(^0.000124t) Get the ln of both sides: ln (0.1) = ln(e(^0.000124t)) ln (0.1) = 0.000124t Now solve for t. Just one clarification, I think the exponent of e...
*July 3, 2015*

**college geometry**

Let x = angle It was said the other angle is 30 deg more than four more the smaller, so Let 4x + 30 = other angle Since complementary angles sum up to 90 deg, x + 4x + 30 = 90 5x + 30 = 90 x = ? Now solve for x. Hope this helps~ `u`
*July 3, 2015*

**chemistry**

Assuming the gas is ideal, we can use Boyle's Law: P1 * V1 = P2 * V2 where P is pressure and V is volume. Substituting, 1.4 * 20.9 = P2 * 12.9 P2 = ? Units in atm. Hope this helps~ :3
*June 18, 2015*

**chemistry**

First write the balanced reaction: 2 NaOH + MgCl2 ---> Mg(OH)2 + 2 NaCl Then we determine the moles of each reactant using the given volume and concentration (molarity). Recall that molarity is moles of solute per liter solution, or M = n / V Solving for moles, n = M * V ...
*June 14, 2015*

**math**

Calculate the determinant (3 x 3 matrix). Then divide it by two and get the absolute value. That's the area. Let the z-coordinate be equal to 1: -10 | 5 | 1 15 | 5 | 1 10 | 12 | 1 The determinant of this set up is 175. Area is therefore, | 175/2 | = 87.5 units Hope this ...
*June 13, 2015*

**Maths**

If that means log 'base 10' then, log (y) + 2*log (x) = 2 Recall that we can rewrite the number that is multiplied by the the log expression as exponent of the term inside the log. For instance, a * log (x) = log (x^a) Thus, log (y) + log (x^2) = 2 Recall that when log...
*June 13, 2015*

**Math**

1/13 = 0.076923 076923 ... You can see here that the repeating numbers are 076923. There are six numbers in all so, 100/6 = 16 remainder 4 Counting four places, the 100th place is 9.
*May 30, 2015*

**Math**

Yes it is. :)
*May 30, 2015*

**MATH**

The given expression could mean a lot of things. It's because of the arrangement and lack of brackets/parenthesis. I suggest you type it again. It could mean for example, 0.4771 = x / (2.303*8.14[(50/323)*373]) Thus in this case, x = 516.42 It could also mean, 0.4771 = (x...
*May 28, 2015*

**Math**

Breadth is also the width. recall that area of rectangle is length multiplied by width: A = l * w Substituting, 900 = l * 45 l = 900 / 45 l = 20 m
*May 28, 2015*

**maths**

The given expression could mean a lot of things. It's because of the arrangement and lack of brackets/parenthesis. I suggest you type it again. It could mean for example, 0.4771 = x / (2.303*8.14[(50/323)*373]) Thus in this case, x = 516.42 It could also mean, 0.4771 = (x...
*May 28, 2015*

**Algebra**

No, it's not C. f(-3) means substitute x = -3 to the function: f(x) = x^2 - 4x + 3 f(-3) = (-3)^2 - 4(-3) + 3 f(-3) = 9 + 12 + 3 f(-3) = ?
*May 28, 2015*

**chemistry**

From the periodic table, the atomic masses of each are: K = 39 Mn = 55 O = 16 Divide the percentage to the respective atomic mass: K: 24.8 / 39 = 0.636 Mn: 34.77 / 55 = 0.632 O: 40.5 / 16 = 2.531 Divide each by the smallest number. The smallest number here is 0.632: K: 0.636...
*May 28, 2015*

**Chemistry**

First we determine the limiting reactant. The molar mass of NH3 is 17 g/mol. Getting the moles of NH3, we just divide the given mass by the molar mass: 25 g / 17 g/mol = 1.47 mol NH3 We determine the moles of NO produced by making mole ratios from the balanced reaction, such ...
*May 28, 2015*

**college geometry**

Use the distance formula: d^2 = (y2 - y1)^2 + (x2 - x1)^2 where d = distance (x1, y1) and (x2, y2) = points Thus, 3.5^2 = (3 - 3)^2 + (7 - b)^2 12.25 = 0 + 49 - 14b + b^2 Now solve for b.
*May 27, 2015*

**Math**

Your answer is actually correct. It should be raised to -6, not -5. For the solution: 1 Light Year = 9.46 x 10^12 km Thus, 58,000,000 km * (1 light year / 9.46 x 10^12 km) = 6.131 x 10^-6 light year
*May 18, 2015*

**Math**

You need to type it again and use parenthesis or brackets. It's necessary, because it's difficult to interpret the expression above.
*May 18, 2015*

**Calculus**

lim f(x) as x-->5 = 7
*May 18, 2015*

**math**

Let x = width Let 2x = length Perimeter of rectangle: P = 2*(length + width) Substitute: 60 = 2*(2x + x) 60 = 2*3x 60 = 6x x = 10 ft (width) 2x = 20 ft (length)
*May 17, 2015*

**Algebra**

This is a Fibonacci sequence, where the next term is the sum of two preceding terms. For instance the 3rd term (which is 1), is the sum of -2 and 3, and the 4th term (which is 4), is the sum of 3 and 1, and so on. Therefore, -2, 3, 1, 4, 5, 9, 14, 23, 37, 60, ...
*May 17, 2015*

**Math**

123 / 350
*May 17, 2015*

**Math**

Light Year is the distance traveled by light in one year. The speed of light in vacuum is approximately 3 x 10^5 km/s. And 1 year = 31,536,000 seconds. Thus, 1 Light-Year = 3 x 10^5 km/s * 31,536,000 s = 9.4608 x 10^12 km
*May 17, 2015*

**Math**

The geometric sequence is 1/4 , 1/16 , 1/64 , 1/256 , ... And the ratio is r = 1/16 / (1/4) = 1/4 This infinite geometric sequence converges because the ratio is in the range of -1 < r < 1. Getting the sum, we use the formula, S = a1 / 1 - r S = 1/4 / (1 - (1/4)) S = 1/4...
*May 17, 2015*

**maths**

String P is 3 times as long as string Q: P = 3Q String R is 3m longer than half the total length of strings P and Q: R = (1/2)(P + 3Q) + 3 The total length of all three strings is 5400 cm: P + Q + R = 5400 Substituting (such that everything is in terms of Q): 3Q + Q + (1/2)(3Q...
*May 17, 2015*

**Geometry**

Let n = pints of blue paint needed Use ratio and proportion. 3 blue : 4 red = n : 14 red Rewriting, 3/4 = n/14 n = (3/4) * 14 n = 42/4 n = 21/2 pints of blue paint
*May 17, 2015*

**science**

Percent Yield = (Actual Yield / Theoretical Yield) x 100 I think your data is insufficient, since we don't know how much is the theoretical yield.
*May 17, 2015*

**maths**

Let x = theta 2 cos(2x - π) = -2 Divide everything by 2 cos(2x - π) = -1 Expand the left side by applying the difference of cosines: cos(A ± B) = cos(A)cos(B) ∓ sin(A)sin(B) Thus, cos(2x)cos(π) + sin(2x)sin(π) = -1 cos(2x)*(-1) + sin(2x)*(0...
*May 17, 2015*

**math**

When an object is immersed completely in water, the displaced volume of water is equal to the volume of the object. The volume of cube is given by V = s^3 where s = side length Thus, V = 5.5^3 V = 166.375 cm^3 The volume of cylinder is given by V = π(r^2)(h) where π...
*May 17, 2015*

**math**

Well you already have the steps. :) (1) First, use the slope formula to find slope: m = (y2-y1) / (x2-x1) From the table of values, let's take the first two points (2,1) and (4,2), and substitute them into the formula for slope: m = (y2-y1) / (x2-x1) m = (2 - 1) / (4 - 2) ...
*May 15, 2015*

**trigonometry**

Recall that sin(A ± B) = sin(A)cos(B) ± cos(A)sin(B) Thus, sin(6x)cos(11x) - cos(6x)sin(11x) = -0.1 sin(6x - 11x) = -0.1 sin(-5x) = -0.1 -sin(5x) = -0.1 sin(5x) = 0.1 5x = sin^-1 (0.1) x = [ sin^-1 (0.1) ] / 5
*May 15, 2015*

**Math**

(sin^2 (x) - 1)^2 = cos(2x) + sin^4 (x) We'll only modify the left side. Expand the left side: (sin^2 (x) - 1)^2 sin^4 (x) - 2 sin^2 (x) + 1 Recall that 1 = cos^2 (x) + sin^2 (x) : Pythagorean identity. sin^4 (x) - 2 sin^2 (x) + cos^2 (x) + sin^2 (x) sin^4 (x) + cos^2 (x...
*May 15, 2015*

**Caclulus**

Yes it is. :)
*May 15, 2015*

**Math.**

4^4 / 4^6 One way to solve this is to expand the numerator and denominator and simplify the fraction to its lowest term. Another way to solve this is to apply some laws of exponent. We can see here that the numerator and denominator has a term with the same base (which is 4). ...
*May 15, 2015*

**math**

Tens = 7 Ones = five less than the tens = 2 Hundreds = four times the ones = 8 Thousands = same as hundreds = 8 Let n = ten thousands digit If their sum is 33, n + 7 + 2 + 8 + 8 = 33 n = 8 Thus the number is 88,872 Hope this helps~ `u`
*May 15, 2015*

**Calc 1**

Derivative of displacement (with respect to time) is velocity. Derivative of velocity (with respect to time) is acceleration. Thus, v(t) = ∫ (a(t)) dt v(t) = ∫ (t + 6) dt v(t) = (1/2)t^2 + 6t + C To find C, you know that at t = 0, v(0) = 4. You can substitute it ...
*May 15, 2015*

**Calc 1-oops**

I mean for the second question, integrate v(t) further and evaluate from t=0 to t=4: D(t) = ∫ v(t) D(t) = ∫ (t^2 + 2t - 3) D(t) = (1/3)t^3 + t^2 - 3t + C at t = 0: D(0) = (1/3)(0)^3 + (0)^2 - 3(0) + C D(0) = C at t = 4: D(4) = (1/3)(4)^3 + (4)^2 - 3(4) + C D(4) = ...
*May 15, 2015*

**Calc 1**

Derivative of displacement (with respect to time) is velocity. Derivative of velocity (with respect to time) is acceleration. Thus, v(t) = ∫ (a(t)) dt v(t) = ∫ (2t + 2) dt v(t) = t^2 + 2t + C It was said that at t = 0, v(0) = -3. v(0) = (0)^2 + 2(0) + C = -3 v(0...
*May 15, 2015*

**Math**

If you draw the figure, you'll have a right triangle with the ladder as the hypotenuse. Let x = how far up the wall the ladder goes We can use sines: sin (angle) = opposite / hypotenuse sin (15°) = x / 12 x = 12 sin (15°) x = ? Units in meters. Hope this helps~ `u`
*May 15, 2015*

**Calc 1**

Check you other posts, the questions are related. Derivative of displacement (wrt time) is velocity. Thus, integral of velocity is displacement. D(t) = ∫(t^2 − 2t − 15) dt D(t) = ? After you solved for the integration, evaluate this from time t=1 to t=7.
*May 15, 2015*

**math**

The amount of flour needed is 1/2 cup more than twice the amount of sugar: 2 * (2 1/2) + 1/2 = 5 + 1/2 = 5 1/2 cups
*May 14, 2015*

**Math 100**

Surface area of a prism: SA = (area of the base) + (lateral area) Imagine the shape. Triangular prism is the shape of a toblerone box. So, SA = 2*(area of triangle) + 3*(area of rectangle) Recall that area of triangle is just A = bh/2 And area of rectangle is A = lw Therefore...
*May 14, 2015*

**Chemistry**

The first one is used, just one arrowhead (not the equilibrium arrow sign).
*May 14, 2015*

**Calc 1**

Use integration to get the exact area: ∫ y dx ∫ x^(1/5) dx Recall that ∫ (x^n) dx = 1/(n+1) x^(n+1) Thus, for example, ∫ (x^2) dx = (1/3)x^3 Try this method on ∫ x^(1/5) dx , and evaluate it from 0 to 32.
*May 14, 2015*

**Calc 1**

We use integration. ∫ y dx = ∫ 6 sin(x) dx = -6 cos(x) | from 0 to π = -6 cos(π) - (-6 cos(0)) = -6(-1) - (-6)(1) = 6 + 6 = 12
*May 14, 2015*

**Calc1**

To get the area, we use integration. From the graph, we can draw vertical strips that run from 0 to π/4. ∫ y dx = ∫ sec^2 (x) dx = tan x | from 0 to π/4 = tan (π/4) - tan (0) = 1 - 0 = 1
*May 14, 2015*

**math**

If you draw this you'll have a figure of a rectangle with a triangle on its top. The base of the triangle is 12 meters (equal to side length of rectangle). Half of the base is 6 m, and drawing a line as the height of the triangle, you can form two right triangles. Thus, ...
*May 14, 2015*

**math**

(2a + 3b)(2a − 3b) Distribute each factor or use the FOIL method. = (2a)(2a) + (2a)(-3b) + (3b)(2a) + (3b)(-3b) = 4a^2 - 6ab + 6ab - 9b^2 = 4a^2 - 9b^2
*May 14, 2015*

**maths**

I don't know the SMALLEST number that should be multiplied to 103875 to make it a perfect square. But the most obvious answer here is to multiply it by 103875 (the number itself), since 103875 * 103875 = 103875 ^ 2
*May 14, 2015*

**Algebra please help**

1. Yes 2. Yes 3. Yes 4. Yes 5. Yes
*May 14, 2015*

**Algebra 104**

Let x = side length of square discarded The volume of rectangular solid is given by V = lwh where l, w and h are the length, width and height respectively. When the flaps are folded up, it acquires a height, and this height measures x inches, since you cut a square with a side...
*May 13, 2015*

**geometry**

This actually depends on you definition of faces and edges. If face is not necessarily flat, and edge is where two faces meet, then A cylinder has 3 faces, 2 edges and 0 vertices. Area of the base of cylinder: A cylinder has base in shape of circle, and there are two circles...
*May 13, 2015*

**Math**

To solve algebraically, a 4 two-credit courses has total of 4 x 2 = 8 credits. Substituting to the equation, T = (1/4)c + 6 T = (1/4)(8) + 6 T = 2 + 6 T = 8 Since the units of T is in hundreds of dollars, the tuition is $800. I'll leave the graphing to you since graph ...
*May 13, 2015*

**maths**

When an object is immersed completely in water, the displaced volume of water is equal to the volume of the object. The volume of cube is given by V = s^3 where s = side length Thus, V = 5.5^3 V = 166.375 cm^3 The volume of cylinder is given by V = π(r^2)(h) where π...
*May 13, 2015*

**Physics**

The object is experiencing uniformly accelerated motion (UAM). We can apply the formula: h = (vo)(t) - (1/2)(g)(t^2) where vo = initial velocity t = time g = acceleration due to gravity = 9.8 m/s^2 Solving for the height after 2 seconds, h = 37(2) - (1/2)(9.8)(2^2) h = 54.4 m ...
*May 13, 2015*

**Math-oops**

Sorry. I see that r = 0.81 according to the problem, not 0.8. Well substituting again, d = 16 + (0.81)(32 / (1 - 0.81)) d = 152.4 ft.
*May 13, 2015*

**Math**

This is an example of infinite geometric sequence. Formula for sum of infinite geom sequence: S = a1 / (1 - r) Total distance traveled: d = (distance ball dropped) + (1st bounce up) + (1st bounce down) + (2nd bounce up) + (2nd bounce down) + ... d = 16 + 16(0.8) + 16(0.8) + 16...
*May 13, 2015*

**Math**

In an arithmetic sequence, an = a1 + (n-1)d where an = nth term a1 = first term n = number of terms d = common difference The sixth term is 20.6 so, 20.6 = a1 + (6-1)d 20.6 = a1 + 5d The ninth term is 30.2 so, 30.2 = a1 + (9-1)d 30.2 = a1 + 8d Now you have two equations, to ...
*May 13, 2015*

**Functions**

Even: Algebraically, we substitute x as -x and if it goes back to original function, then it's even. Thus, f(-x) = f(x). Visually, if this function is graphed and you see that it is symmetric to y-axis, then it's even. Odd: If f(-x) = -f(x). I will assume the function ...
*May 13, 2015*

**Math: Line Symmetry and Reflection**

1. Yes 2. It's D, since y-coordinate is increased by 3. 3. Yes 4. If a point is reflected over the x-axis, the y-coordinate of the point changes its sign to opposite. So the points become A'(2,5), B'(-3,-5) and C'(3,3).
*May 13, 2015*

**college math**

In the word "Tallahassee", there is only one letter T out of 11 letters, so the probability of getting a T is 1/11. There are 2 letter E in the word, so probability of getting an E is 2/11. The probability of getting a letter T OR letter E is therefore 1/11 + 2/11 = ...
*May 13, 2015*

**College math**

In the word "Tallahassee", there is only one letter T out of 11 letters, so the probability of getting a T is 1/11. There is no letter F in the word, so probability of getting an F is 0/11 or 0. The probability of getting a letter T OR letter F is therefore 1/11 + 0...
*May 11, 2015*

**math**

159 gallons are being burned per second, so if two seconds have passed, 159 x 2 = 318 gallons Thus, to get the total volume in gallons burned after some time, we just multiply the rate (159 gal/s) by the time passed (in seconds). So if three seconds have passed, 159 x 3 = 477 ...
*May 11, 2015*

**math**

Let x = food or meal Thus the share of each men is x/120. And the share of each children in x/200. It was said in the problem that 150 children took the meal, so the total meal taken by these children is number of children multiplied by the share of each: 150 * x/200 = 3x / 4...
*May 11, 2015*

**math**

Formula for slope: m = (y2 - y1)/(x2 - x1) Take the first two points: m = (-1 - 1)/(6 - 3) m = -2/3
*May 7, 2015*

**maths**

Yes that's right. You have to equate the expressions for widths and for the lengths, since left and right widths (and lengths) have the same dimensions. You may rewrite the equation for y=3x+3÷6 as y = (3x + 3)/6 And now you have an expression for y, we can ...
*May 7, 2015*

**Algebra 2**

Tangent is opposite / adjacent, so we can say that in tan (theta) = 1/2, the 1 and 2 are the sides of the right triangle and c^2 = a^2 + b^2 c^2 = 1^2 + 2^2 c = sqrt(5) is the hypotenuse. Cosine is adjecent / hypotenuse, so cos(theta) = 2 / sqrt(5) Method is the same for other...
*May 7, 2015*

**Math**

1/10
*May 7, 2015*

**Pre-Algebra (Probability)**

Let n = number of sections If 2/3 of n is the number of even numbered sections, which is 8, then, (2/3)n = 8 n = 12
*May 7, 2015*

**PreCal**

2|5x - 5| + 4 = 20 There are two cases here, where the absolute value term is + or - Case 1: 10x - 10 + 4 = 20 10x - 6 = 20 10x = 26 x = 2.6 Case 2: -10x + 10 + 4 = 20 -10x + 14 = 20 -10x = 6 x = -0.6
*May 7, 2015*

**physics**

Use the formula: h = vo*t - (1/2)gt^2 Since the rock experiences freefall, initial velocity (vo) is zero: h = -(1/2)gt^2 Substitute: h = -(1/2)(-9.8)(3.8^2) h = ?
*May 7, 2015*

**physics**

Use the formula: h = vo*t - (1/2)gt^2 We know that vo = 41 g = 9.8 h = 0 (since it strikes the ground) 0 = 41t - (1/2)(9.8)t^2 Solve for t. One of the answers is t = 0, but this is the time before the release of the ball. Get the other value of t.
*May 7, 2015*

**math**

3 x 20° = 60°
*May 7, 2015*

**Chemistry**

A gas 'collected over water' is a mixture of water vapor and the gas. So P,total = P,gas + P,water vapor You'll solve for P,gas and to do that, you'll need data for vapor pressure of water at 23 C. P,water vapor = 21.1 mm Hg (different sources may show ...
*May 7, 2015*

**Math 222**

Yes that's right. `u` Domain is all real numbers or (-infinity, +infinity). And range is (-infinity, 4] since the highest value of g(x) occurs when x^2 is zero. Yes, the graph is a parabola with a maximum (its vertex) which is at point (0,4)
*May 4, 2015*

**Math 222**

You take some values of x. Then substitute them to the equation to get the corresponding y values. Plot the points. For instance, y = -x^2 at x = 0, y = -0^2 y = 0 So a point on the graph is (0,0) at x = 1, y = -1^2 y = -1 So a point on the graph is (1,-1) at x = -1, y = -(-1...
*May 4, 2015*

**physics**

Assuming ideal gas, use the formula P1 * V1 / T1 = P2 * V2 / T2 Substitute the given, and don't forget to convert temperature to absolute temperature (K units). Celsius to Kelvin conversion: K = C + 273
*May 4, 2015*

**Precal**

f(g(x)) = 4(8x+1) - 4 f(g(x)) = 32x + 4 - 4 f(g(x)) = 32x as x ---> 0, = 32(0) = 0
*May 4, 2015*

**chemistry**

The dilute acid we're talking about here is H2SO4. So the reactants involved are Cu and H2SO4. The product of this reaction is CuSO4·5H2O. This is the pale blue solution.
*May 4, 2015*

**algebra**

A. Well you just substitute a and b: √a * √b √18 * √10 To combine them, we just multiply the terms inside the radical sign and retain the radical sign: √180 √(36*5) √(6^2)(5) 6√5 B. Well we know that 6√5 is also equivalent ...
*May 1, 2015*

**algebra(???)**

What's the question...? `u` But I'm assuming that these values of x are roots, and you need to find the polynomial which has these roots. If that's the case, you substitute the values of roots here: (x - root1)(x - root2)(x - root3) = 0 (x + 7)(x - 7)(x - 5/6) = 0 ...
*May 1, 2015*

**algebra**

#1. It's not in simplified form because there's a radical sign in the denominator. to remove the radical sign, we multiply both numerator and denominator by √3: (3 / √3) * (√3 / √3) = 3√3 / 3 = √3 #2. Yeah, it's already in ...
*May 1, 2015*

**physics**

We use the formula g = GM / r^2 where g = acceleration due to gravity (m/s^2) G = gravitational constant = 6.673 x 10^-11 N-m^2-kg^2 M = mass of larger body (kg) r = distance from center of mass of the body Here, the total distance from the center of earth to the satellite is ...
*May 1, 2015*

**MATH**

Use distance formula (point-to-point): d = sqrt((y2 - y1)^2 + (x2 - x1)^2) where (x1,y1) and (x2,y2) are the points involved. In the problem, it was said that the distances from A -> B and A -> C are equal. Therefore, sqrt((4 - 2)^2 + (3 - a)^2) = sqrt((1 - 2)^2 + (-2 - ...
*May 1, 2015*

**Math**

Let x = number of quarters since she has twice as many dimes as quarters, Let 2x = number of dimes The total value in $ is 0.25x + (0.10)(2x) And it was said that when the numbers of quarters and dimes are interchanged, she would have $1.20 more than the original. So, (New ...
*May 1, 2015*

**Chemistry**

In the balanced chemical reaction, SO2 + 2 Cl2 ---> SOCl2 + Cl2O We make a mole ratio of the species involved, which is Cl2O : Cl2. That is, for every 2 moles of Cl2 reacted, 1 mole of Cl2O is produced, or 1 mol Cl2O / 2 mol Cl2 We are given 0.400 moles of Cl2, and it was ...
*May 1, 2015*

**Chemistry**

Density is simply mass per unit volume. ρ = m / V Useful conversions: 1 L = 1000 mL 1 g = 1000000 µg Substitute the values to the formula, and convert.
*May 1, 2015*

**Chemistry**

Dilution formula: M1 * V1 = M2 * V2 where M = molarity V = volume Substitute: 8.25 M * 25 mL = 2.40 M * V2 Now solve for V2 and don't forget to convert it to Liters.
*May 1, 2015*

**chemistry**

#1. Balance the chemical reaction first. 2 Na2O2 + 2 H2O −--> 4 NaOH + O2 #2. Then calculate the molar mass of Na2O2 and O2. From the periodic table, Na - 23 and O - 16. Thus, Na2O2 : 2*23 + 2*16 = 78 g/mol O2 : 2*16 = 32 g/mol #3. Get the moles of Na2O2 from the ...
*May 1, 2015*

**Algebra**

The English alphabet consists of 26 letters, but since x, y and z are not used, we'll have 23 letters to choose from. From 0 to 9, there are 10 numbers total, but there's restriction that the last digit cannot be 0 or 9, so that's 8 numbers total to choose from for...
*April 30, 2015*

**algebra 2**

The term with highest degree of x is 10x^3. The degree is 3 (exponent of x), and the leading coefficient is 10 (the numerical coefficient of 10x^3).
*April 30, 2015*

**Math**

Area of triangle: A = (1/2)bh Area of circle: A = (π/4)d^2 The remaining area is therefore, (1/2)bh - (π/4)d^2 Substituting, (1/2)(8)(7) - (π/4)(3)^2 = ? Units in in^2. Hope this helps~ `u`
*April 30, 2015*

**Math**

14/165
*April 30, 2015*

**math**

Volume of rectangular box is length x width x height: V = l*w*h Area of the base is also length x width, so V = (area of the base)*h 18 = (4.5)*h h = 18 / 4.5
*April 27, 2015*

**Chemistry**

Ammonium Nitrate is NH4NO3 We need the get the molar mass of this. From the periodic table, the masses of each element in the chemical formula N - 14 H - 1 O - 16 So for NH4NO3, 14 + 4*1 + 14 + 3*16 = 80 g/mol To get the number of moles, we simply divide the given mass by its ...
*April 27, 2015*

**math**

4/8 + 3/8 To add this fraction, first make sure their denominators are equal. Their denominators are already equal (which is 8). And so we can combine now their numerators while denominator stays the same: (4 + 3)/8 = 7/8
*April 27, 2015*