Monday

July 28, 2014

July 28, 2014

Total # Posts: 24,006

**Language Arts Grade 8**

You can find the table of contents at amazon.com: http://www.amazon.com/Popol-Vuh-Definitive-Edition-Glories/dp/0684818450#reader_0684818450

**math**

.05 * 25000 = ? Since you mention two increases, I'm not sure just what is to be done. I would not expect the COL increase to include the merit increase.

**geometry**

There is no apothem. Only regular polygons have one. In this case, the lateral area is the three faces of dimensions 3x6, 4x6, 5x6 The volume is v=Bh where B is the area of the base, 1/2 (3)(4)

**Algebra 2**

If we try to solve this algebraically, we run into trouble. x^2 + y^2 = 1600 x^2 + (1/40 (x-40))^2 = 1600 x^2 + 1/1600 (x-40)^4 = 1600 (x-40)^4 + 1600x^2 = 1600^2 Now, that's a hard one. However, if you examine the two equations, you see that the first is a circle of radiu...

**Math please check my answer?**

Not B, that's for sure. The x-intercept is where y=0. Plug that in and you get 6x=30 Similarly, if x=0, we get 11y = 30 The values in B are the reciprocals of the true answers.

**appliance repair**

I guess the context of the subject, the question and its choices would indicate that the class is in electricity or electronics, and not physics. Not much call for Electric Field strength in appliance repair... :-)

**physics**

conserve momentum: .02*80 = 100v

**English**

#2. read up on restrictive qualifiers. They don't use the comma.

**math**

Back to the drawing board. Try 1B 2B 4C 8A 9D are you just guessing here? I'm especially intrigued at #2, since I gave you the answer! It would have helped had you actually shown your work. Then I might have been able to show you where you went wrong.

**math**

#1. Interesting. 1/5 of 60 is 12. So I'd be interested to know how you figure a 2/5 increase is only $9. #2. Interesting. 4 days at $40/day would only be $160, and she paid less than that. 12.5 cents is about 10% of 380 or about $40 So, an estimate would be about $200. How...

**Maths**

No, a=2b a+b = 40 2b+b = 40 ?? Not an integer solution Also, you started out saying a=boys and b=girls. Then you say b=2a, but that's not correct. The whole problem looks mishandled.

**Algebra**

this is just a quadratic, so the max is reached at x = -b/2a = -500/-50 = 10

**Math**

the new balance is just old balance + finance charge - payment.

**Calculus**

f(x) = 2x^3 - 3x^2 - 72x + 7 f'(x) = 6x^2 - 6x - 72 = 6(x^2-x-12) f"(x) = 12x-6 = 6(2x-1) f'=0 at x= -3 and 4 f"=0 at x = 1/2 Now it's easy to answer the questions. f is increasing where f' > 0 f is concave up where f" > 0 no asymptotes, so...

**Algebra**

(9x+1)(2x-3) = 0

**Algebra**

(1/2)^3

**Math**

6+2x = 48 Looks like 21 DVDs. Naturally, the total cost would be $48, since the 2nd plan always costs that.

**furthermathematics**

the horizontal distance is x(t) = u cosθ t The time taken to go 20m is thus t = 20/(u cosθ) The trajectory is y(t) = u sinθ t - g/2 t^2 We know that y=0 at 0 and 20/(u cosθ), so the max height is reached at 10/(u cosθ). So, u sinθ * 10/(u cosθ...

**Math 6 gemoetery**

Good call, Damon. By rounding down to 90 I neglected the rather sizable underestimate of 2.47 by 2.00.

**Math 6 gemoetery**

Rounding each value to the nearest single-significant-digit approximation, that would be 90x60x2 I'd choose that instead of 100*60 because in that case both values are rounded up, making the estimate too high.

**Algebra**

2x+5 > 1 x > -2 So, of the 10 numbers, how many are greater than -2?

**math ~dont know all but check some~ pls help!!!**

#1 x^2+2x+4 can be written as x^2 + x(2) + 4*1^2 I think that the best choice would be 1 big square, 1 tall rectangle, 4 little squares #2 –3f^2 + 4f – 3 + 8f^2 + 7f + 1 just collect terms of the same power (-3+8)f^2 + (4+7)f + (-3+1) 5f^2 + 11f - 2 #3 (2x^2 + 6x + 1...

**maths/permutation and combination**

You have to have the 2 or 3 as the first digit. After that, the other 3 digits can be done in 3! = 6 ways. So, the total is 2*3! = 12

**Calculus**

the gradient is the slope of the tangent to the curve. y' (x) gives the slope of the tangent for any value of x. So, at x=0, y'(x) = 2-0 = 2, so the gradient is 2 at the point (0,2) See the graphs at http://www.wolframalpha.com/input/?i=plot+y%3D2x-x^2%2Cy%3D2x

**Calculus**

y = 2x-x^2 y' = 2-2x so, where is 2-2x = 2?

**maths**

these are standard values. plug them in; what do you get?

**maths**

GRR! PI, not pie! sin pi/6 = cos pi/3 = 1/2 tan pi/4 = 1 so, we have 1/4 + 1/4 - 1 = -1/2 I suspect a typo

**Maths**

Uh, geez -- I believe I just did. Given two points, find the midpoint of the line connecting them. Find the slope of that line, and take its negative reciprocal. Now you have a point and a slope. Just write the equation of the bisecting line.

**Maths**

Yes. P and Q cannot be as given. All of the choices have slope 7/4 or -7/4.

**Maths**

the bisector goes through the midpoint of PQ. That is (-3/2,-3/2) PQ has slope -5/7, so the perpendicular has slope 7/5 Now you have a point and a slope, so the line is y+3/2 = 7/5 (x+3/2) 10y + 15 = 14x + 21 10y-14x-6 = 0 I suspect a typo. If you graph the two lines, you will...

**Calculus**

dN/N = -k dt log N = -kt N = e^(-kt) Now, we know that the fraction left after t years is (1/2)^(-t/5730) So just use the fact that 1/2 = e^-log2 and you can find k.

**Calculus**

use discs or shells. v = ∫[0,2] πr^2 dy where r = x or v = ∫[0,√2] 2πrh dx where r=x and h=y

**Calculus**

a = ∫[0,1] (2x-x^2)-(x^2) dx

**Calculus**

1/(x+2) + 1/(x-2)

**Calculus**

u = x : du = dx dv = e^x dx : v = e^x ∫u dv = uv - ∫v du = xe^x - ∫e^x dx I expect you can take it from there.

**Calculus**

u = x^2-1 du = 2x dx, so x dx = du/2 ∫1/2 u^3 du

**fifth grade math**

8/15 * 1/4 = 2/15

**Calculus - incomplete**

what specifications? what were the measurements?

**Math 8th gr.**

27 - (-9) (-2) ÷ 3 * (-4) - 0 - 33 - (-39) 27 - 18 ÷ 3 * (-4) - 0 - 33 - (-39) 27 - 6 * (-4) - 0 - 33 - (-39) 27 - (-24) - 0 - 33 - (-39) 27 + 24 - 0 - 33 + 39 51 - 0 - 33 + 39 51 - 33 + 39 18 + 39 57

**math**

-15 - (3-7) + 6 * (-2) + (-8) - 9 -15 - (-4) + 6 * (-2) + (-8) - 9 -15 + 4 - 12 - 8 - 9 -40

**math**

draw a number line mark it off in units of 1/6 using a different color, mark it off in units of 1/2 You will see that the 3rd mark on the 1/6 line is the same as the first mark on the 1/2 line.

**Precalculus**

It is true that Reiny's answer has a typo. Recognizing that, fix it and rearrange it into the desired form of the equation.

**geometry**

h/19 = tan52°

**geometry**

you have a right triangle, with vertical leg = 480 horizontal leg = 340 so, the angle θ from the horizontal base is tanθ = 480/340

**Science**

A skydiver prepares to jump out of a plane. Explain how gravity and air resistance will affect the motion of the skydiver before and after he or she opens the parachute.

**Science**

Use Newton's 1st law of motion to explain how wearing a seat belt in a moving car could help prevent injury.

**math**

a circle with center at (h,k) with radius r is (x-h)^2 + (y-k)^2 = r^2 Now just read off the values from your equation.

**Math**

you want to get m by itself. First, get everything with m on one side, and the rest on the other. Since both sides are equal, if you do the same thing on both sides, they remain equal. So, subtract 12 from both sides. That gives you 4m = 12 Now divide by 4 on both sides. That ...

**Calculus**

a = pi r^2 da/dt = 2pi r dr/dt Now plug in r and dr/dt to get da/dt.

**trigonomertry math**

we are in QIV, so sinA = -√8/3 Now just plug in the values for sinA and cosA to evaluate your expression.

**Calculus**

just find t where dd/dt = 0

**Calculus 1**

well, draw a diagram. If the width is x, then the length is 1000-2x. So, the area is a = x(1000-2x) = 1000x-2x^2 da/dx = 1000-4x da/dx=0 when x=250 As is usual, you will find that for maximum area, the fencing is divided equally among the widths and lengths. In this case, that...

**Calculus 1**

500x250

**Trig help**

3sinθ = sinθ - 1 I suspect a typo, but as things stand, 2sinθ = -1 sinθ = -1/2 since sin π/6 = 1/2, and sinθ < 0 in QII,QIV, we have θ = π+π/6 and 2π-π/6

**algebra**

No idea at all?

**math**

no; could be a rhombus, a kite, or even a trapezoid.

**mathhhh!**

wherever there is an x, make it a -2: f(-2) = (-2)^2 = (-2)(-2) = 4

**Science**

A person roller skates down a street heading West. What is true about friction in this case? the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward my answer is # 4

**Calculus**

secants connect two points on the graph. The slope of the secant is the average rate of change during that interval. The tangents are just secants where the interval has zero length -- their slopes are the instantaneous rates of change. The initial instantaneous rate is just t...

**Science**

thank you

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball? the choices are 0N 3N 6N 12N I think its 6N

**Algebra, math,**

a^6-b^6 = (a^2)^3 - (b^2)^3 = (a^2-b^2)((a^2)^2+(a^2)(b^2)+(b^2)^2) = (a-b)(a+b)(a^4+a^2b^2+b^4) now do the division and you are left with (a-b)(a+b) = a^2-b^2

**Algebra, math,**

since time = distance/speed, 700/(120-x) = 720/(120+x)+2 x = 20

**Math**

try some grouping: c^2(a-b) - a^2(a+b) + b^2(a+1) That pesky 1 at the end makes me think there's a typo. All the terms are degree 3 except that lone b^2. I suspect there may also be a sign mixed up somewhere as well. Are you sure that's the way it is?

**Science**

thank you

**Science**

A 2,500 kg car moves at 15 m/s squared, 15 m/s squared is the ? a-acceleration b- force c- velocity d-speed My answer is speed

**maths**

x = 21/(x-4) just by inspection, since the factors of 21 are 3 and 7, with one 4 less than the other, that's what I'd expect for roots of the equation. x(x-4) = 21 x^2-4x = 21 x^2-4x+4 = 21+4 (x-2)^2 = 25 x-2 = ±5 x = 2±5 That is, 7 or -3 We can't use...

**maths**

you can read the x-intercepts right off the original equation once you expand it to the desired form, the y-intercept is just the value of c. The vertex (turning point) is midway between the x-intercepts. Since the coefficient of x^2 is positive, the parabola opens upward.

**maths**

just solve for t in 520-5t^2 = 0

**Math**

I don't think this is determined. Take a look at http://mathcentral.uregina.ca/QQ/database/QQ.09.07/h/amanda1.html and you can see that depending on how you divide the diagonals, the median can be a variety of lengths.

**math**

correct until the last line. 7x+5(x+30) = 7*75 + 5*105 = 525+525 = $10.50

**Algebra 1**

If the old cloth had side s, the new cloth satisfies (s-2)(s+2) = 780 26x30

**Math**

the solutions are x = (3±√13)/2 pick the values close to those.

**Physics**

and she moves away from him at 3/4 his speed.

**Calculus- answer check**

Since R"=0 at t=2 and t=4, I see two inflection points. R'=0 at t=1 and t=4. Since R' and R" are both zero at t=4 (because of the multiple root there), there is no max/min at t=4. At R"(1)>0, so that's a local minimum. Not sure about the false sig...

**Math**

Looks to me like you have a typo. I get 1,11,21,1211,111221,312211,13112221,... or even 1,11,21,1211,3112,211213,312213,...

**Algebra 1--Please, help me!**

well, shoot. How do you graph any function? You pick some values for x, compute the value for y, and plot some points. Then draw a curve through the points. For y = 200/x + 5, start with x=1 and figure a few points. x y 1 205 2 105 3 71.7 4 55 and so on.

**algebra1**

I get C

**Geometry**

The volume of clay is for a cylinder of radius r is pi r^2(0.75) + pi(r^2-(r-.4)^2)h = 206 Since we have r=4.5, h = 14.6 cm The base is easy, and just subtract that from 206 to get the lateral volume. The lateral surface is just 2pi r h

**Algebra 2**

cos(360-x) = cos(x) so, same as cos 60°

**Math**

for y = a cos(kx) period = 2pi/k amplitude = a

**Algebra**

y^2/9 - x^2/16 = 1 so, what are the foci of y^2/a^2 - x^2/b^2 = 1?

**math Question**

(1-3^10)/(1-3) = 29524

**Algebra**

x^2 = 4py where p = -4 So, ...

**Please help w/ Algebra**

because the perimeter is 56, 2w + 2l = 56 l + w = 28 l = 28-w

**Please help w/ Algebra**

If the field has width w, then the length is 28-w. (w-4)(28-w-4) = 91 w^2-28w+187 = 0 w = 11 The field is 11x17 The smaller area is 7x13 = 91

**math Question**

40/160 = r^2, so r=±1/2

**Science**

A person roller skates down a street heading West. What is true about friction in this case? the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward my answer is # 4

**algebra 2**

#1 ok #2 is 80 or -80 b? #3 is a: P(2,3,4,5,6) = 5/6

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball? the choices are 0N 3N 6N 12N I think its 6N

**Algebra 2**

If xy is constant, it's inverse If x/y is constant, it's direct Looks like (b) to me (c) is a bogus answer in any case.

**math**

you are correct.

**math!**

15*12 = 180 330-180 = 150 150/14 = 10 remainder 10

**Multiple Choice**

correct

**Science**

the choices are 1- does not effect the skates 2- pulls the skates eastward 3- pulls the skates downward toward the center of the earth 4- pulls the skates westward

**Science**

A person roller skates down a street heading West. What is true about friction in this case?

**Science**

answers to chose from are 0N, 3N, 6N, 12N

**Science**

If a bowling ball hits a wall with a force of 6 N the wall exerts what force back on the bowling ball?

**math**

1260(1-cos20°)

**Trig**

x^2+11^2 = 24^2 now just solve for x

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