Sunday

April 19, 2015

April 19, 2015

Total # Posts: 30,638

**Pre - CALCULUS**

by precalc you should surely know how to find the roots of a quadratic. What did you get?
*April 10, 2015*

**Calculus**

as usual, begin by drawing a diagram. Clearly, the distance z is the hypotenuse of a triangle with sides 2 and 6. Now, at time t hours from when the car passed the intersection, the distance z is z^2 = (55t)^2 + 6^2 so, when the car is 2 miles past the intersection, t=2/55, ...
*April 10, 2015*

**algebra--1 question**

max height at the vertex, which is at t = 23/4 You should certainly not think that the max height is 11.6, since it started off at 20.
*April 10, 2015*

**algebra 1**

could you be a bit more vague?
*April 10, 2015*

**Math**

so, the area is two trapezoids and four rectangles 2[(8+14)/2 * 18] + 8*11 + 14*11 + 18*11 + 11√(6^2+18^2)
*April 10, 2015*

**physics**

total angular momentum must be constant.
*April 10, 2015*

**Math**

you should know that the sides of a 30-60-90 triangle are in the ratio 1:√3:2 so, the triangle formed by your ladder has sides 3:3√2:6
*April 10, 2015*

**Math**

well, 45 = 3*15 = 3*(3 * 5) 60 = 3*20 = 3*(2^2 5) 180 = 2^2 3^2 5 So, the third number is 3*(3 * 2^2 * 5) = 180
*April 10, 2015*

**Mathematics**

since the ratio is constant, 50/2.25 = x/18
*April 10, 2015*

**geometry**

(a) reflected in y=0 and stretched vertically by 10 (b) shifted left 3 and up 3
*April 10, 2015*

**ANSWER ASAP!!!!!!! PHYSICS**

well, the vertical speed is 9.8t so the probe cannot fall for more than 60/9.8 = 6.12 seconds. That means the plane cannot be higher than 183.67 m high. so, at h meters altitude, with horizontal velocity v, the probe will land with speed s = √(v^2+4h^2) The probe will ...
*April 10, 2015*

**Math**

well, 355 = 1812 but I don't think that is what is wanted.
*April 10, 2015*

**Calculus**

well, you have the formula v = 4/3 pi r^3 dv/dt = 4pi r^2 dr/dt Now just find r from v, and you know that dv/dt = -2, so solve for dr/dt
*April 10, 2015*

**Math**

you are correct.
*April 9, 2015*

**pre - CALCULUS**

better write your function. I can't decipher it. How about f(v) = jlkjasklj if 0 <= v < 1.79 ahahhahas if 1.79 <= v < 20 and so on, each section on its own line. And you can lose those 𝑡 characters, which show up as small boxes on my browser.
*April 9, 2015*

**Mathw(URGENT pls)**

use induction. Let the sum be f(n) for k=1, it is clear that 1/(1*2*3) = 1(4)/(4*6) Now assume true for k=n and see what happens for k=n+1 1/(1*2*3) + ... + (2n-1)/(n(n+1)(n+2)) + (2(n+1)-1)/((n+1)(n+2)(n+3)) = n(3n+1)/(4(n+1)(n+2)) + (2n+1)/(n+1)(n+2)(n+3) = n(3n+1)(n+3) + 4(...
*April 9, 2015*

**Mathw(URGENT pls)**

I get n(3n+1) --------------- 4(n^2+3n+2) How did you do it?
*April 9, 2015*

**Calculus**

y = 1/(1+be^kt) y' = kbe^kt/(1+be^kt)^2 y' will be greatest when y" = 0 y" = k^2be^kt(3e^kt-1)/(1+be^kt)^3 so, that will be when t = -1/k ln3 In this case, when t = 1.48
*April 9, 2015*

**Earth Science**

thank you
*April 9, 2015*

**Earth Science**

Which of the following are you most likely to experience a-total solar eclipse b-total lunar eclipse c-full moon d-partial lunar eclipse? my answer is full moon
*April 9, 2015*

**Math**

A is what you want B is just y = 8x C is y = (12-4)x D is y = 12x - 12*4 = 12(x-4)
*April 9, 2015*

**Calculus**

f(x) = √(2x) g(x) = f^-1(x) = x^2/2 f'(x) = 1/√(2x) g'(x) = x So, we want 1/√(2c) = c 1/2c = c^2 1/2 = c^3 c = (1/2)^(1/3)
*April 9, 2015*

**Calc AB**

clearly, since f'(-3) = 0, f^-1 has a vertical tangent at x = f^-1(-3) = 2.
*April 9, 2015*

**Calc AB**

Looks like D to me
*April 9, 2015*

**Calc AB**

Hint: dx/dy = 1/(dy/dx)
*April 9, 2015*

**Calculus AB**

well, f^-1(x) = 9-x^2, so ...
*April 9, 2015*

**Chem**

Volume of nitrogen gas is 125ml atmospheric pressure is 763mm Hg the water temperature inside the eudiometer is the same as the level of the water in the beaker. Calculate the volume if the nitrogen at STP. P1V1/T1=P2V2/T2
*April 9, 2015*

**Calc**

that is just the integral of 3x^-6 - 4|x| just use your power rule.
*April 9, 2015*

**Integral**

just use the power rule on u^(-5/4) + 5.5 u^(1/2) du
*April 9, 2015*

**Calculus**

y=2x xyz=k, so z=k/2x^2 the cost c is c(x,y,z) = 6xy + 10(2xz + 2yz) c(x) = 6x(2x) + 20(3x)(k/2x^2) = 12x^2 + 30k/x
*April 9, 2015*

**math (explanation and answer)**

The circumference of the original paper is 2πR If the arc AB subtends an angle θ, then the circumference of the cone formed is 2πR - Rθ = R(2π-θ) So, the radius of the cone is r = R(1-θ/2π) Since the slant height of the cone is still r, ...
*April 9, 2015*

**math**

y=3
*April 9, 2015*

**calculus (please with steps and explanations)**

This was done by Damon, but here's my take ∫[0,5](f(x)+2) dx = ∫[0,5] f(x) dx + ∫[0,5] 2 dx = 4 + 2x[0,5] = 4 + 10 = 14 Since we are dealing with an even function, ∫[-5,5] f(x) dx = 2∫[0,5] f(x) dx = 2*4 = 8
*April 9, 2015*

**Calculus**

I can't see the diagram, but it appears that if the shadow is x, then 25/x = tanθ so, -25/x^2 dx/dt = sec^2θ dθ/dt -25/2500 dx/dt = (1+1/4)(-1/4 * π/180) Now just solve for dx/dt
*April 9, 2015*

**Algebra 1**

well, since they are usually written as y = a * b^x it seems pretty clear, wouldn't you say?
*April 8, 2015*

**physics**

If the first object takes t seconds to hit, h - 4.9t^2 = 0 t = √(h/4.9) the second object is thus h-4.9(t-1)^2 = 20 h = 31.63 m
*April 8, 2015*

**Math**

Thomas put 1/4 of the c coins he had in his pocket into the jar under his bed. He put 16 coins into the jar. The equation that models this situation is 1/4c = 16. How many coins did Thomas have in his pocket? a 4 coins b 12 coins c 20 coins d 64 coins The answer would be c.
*April 8, 2015*

**AP CALC**

since x^2+y^2+z^2 = 4 using symmetry, we can take 8 times the volume in the first octant. Then v = 8∫[0,2] ∫[0,√(4-x^2)] ∫[0,√(4-x^2-y^2)] dz dy dx
*April 8, 2015*

**Math**

no. rays might be parallel such an angle of zero measure could be said to fit the constraints, but that might not be allowed.
*April 8, 2015*

**calculus**

assuming an open box, then x^2 + 4xz = 426 v = x^2 z = x^2 (426-x^2)/4x = 426x - x^3
*April 8, 2015*

**Math didn't post problem right**

find the Quotient: 1,754/21 a 1733 b 21 11/83 c 83 11/21 d 1775 Is C the correct answer. I had post the problem wrong. Sorry
*April 8, 2015*

**Math**

find the quotient: 1,754/12 a 1733 b 21 11/83 c 83 11/21 d 1775 Would C be the correct answer?
*April 8, 2015*

**Math**

I agree.
*April 8, 2015*

**Math**

The determinant |2 6| |1 3| = 6-6 = 0 So, there is no inverse
*April 8, 2015*

**Algebra**

Better think again, S. the line x=4 is a vertical line The vertical line through (-6,-2) is x = -6
*April 8, 2015*

**Algebra 2 math**

the triangle's 3rd side is √(41^2-40^2) = 9 So, now you know all three sides, and the angles, so the trig functions are easy to read off. sin G = 9/41 and so on
*April 8, 2015*

**linear algebra-urgent**

you know p. Can you not figure its length? √(33^2+44^2) = 55
*April 8, 2015*

**linear algebra-urgent**

#1 a unit vector in the direction of w is z=[3/5;4/5] p = u.z = 11/5 z = [33/25;44/25] = [1.32;1.76] you are correct |kp| = k|p| = 55/25 k So, k = 25/55 As for the span, that is usually defined for a set of vectors. span{w} would just be w. So, any vector orthogonal to w will ...
*April 8, 2015*

**math**

54.2/16 * 2.31
*April 8, 2015*

**math**

Not even close. The area is length * width, or 8(6x+3) = 48x+24 6x+3 is not 9x. Even if it were, 9x+8 would be half of the perimeter, not the area.
*April 8, 2015*

**Geometry**

wrong. The two circular ends of the cylinder are usually parallel. I guess that leaves only one other possibility, right?
*April 8, 2015*

**math**

well, just start listing them: 3568 3586 ... 8653 There are only 24 of them.
*April 8, 2015*

**Algebra**

If Nathan is x and Nicole is y, we have y = 2/3 x (y-2) = 1/2 (x+5) Now just solve for x.
*April 8, 2015*

**Math (Please help ASAP)**

It's just a quadratic in p: q+p^2-33p = 9 p^2 - 33p + (q-9) = 0 Now just use the quadratic formula to get the two values for p.
*April 8, 2015*

**Math**

1/3 (9x-2) + 1 = 2(4x+1) You can multiply by 3 to get 9x-2 + 3 = 6(4x+1) 9x+1 = 24x+6 -5 = 15x x = -1/3
*April 8, 2015*

**chemistry**

CuS + 2HNO3 = Cu(NO3)2 + H2S That should help, right?
*April 8, 2015*

**trigonometry**

speed = distance/time, so 2π*3960mi/24hr = ? mi/hr 2πrad/24hr = ? rad/hr
*April 8, 2015*

**trigonometry**

v = 2π*14in/rev * (.5/2π)rev/s = 28 in/s .5rad/s * 1rev/2πrad * 60s/min = 4.77 rev/min .5rad/s * 180°/πrad = 90/π °/s
*April 8, 2015*

**maths**

this is just an A.P. with d = 4 a = 100-20*4 = 20 So, the sum of 21 rows is S = 21/2 (20+100)
*April 8, 2015*

**math**

draw your triangle the other side is √15 since we are in QII and sin is positive, x = -√15 y = 1 r = 4 so, cosx = -√15/4 Now use those values to plug into your half-angle formulas.
*April 8, 2015*

**Pre-calc**

Or, you can go the other way sin(7x) = sin(6x)cos(x) + cos(6x)sin(x) and start expanding those as well, till all you have left is a bunch of sin(kx).
*April 7, 2015*

**Pre-calc**

http://www.wolframalpha.com/input/?i=%28sinx%29%5E7 will show the answer you need. sin^7 = sin(1-cos^2)^3 Now you can start expanding and using the sum formulas. I'm sure a google search will show up all the gory details.
*April 7, 2015*

**math**

why use } when / is available? (4/9)(1/8) = 1/18 (1/18)(1/3) = 1/54
*April 7, 2015*

**Math**

correct.
*April 7, 2015*

**Math**

There is clearly a typo in the above, since the function is a parabola which opens upward, and so has no maximum. If we go with y = -6x^2+42x-60 then that works out to y = -6(x^2-7x+10) = -6(x-5)(x-2) The vertex is at x = 3.5, so that means 3500 boards. You know, if you keep ...
*April 7, 2015*

**Math**

-5x^2 - 30.5x = -1/10 (50x^2 - 305x) = -5/10 x (10x-61) I suspect a typo, since the roots of the above are clearly 0 and 6.1
*April 7, 2015*

**Math**

no, it can be any real number.
*April 7, 2015*

**Calculus**

see the related questions below.
*April 7, 2015*

**math**

I'd think so, since the eye perceives the linear dimensions, which grow much more slowly than the volumes.
*April 7, 2015*

**I NEED HELP WITH THIS**

how far do you get? Do you not have any ideas? If not, you'd better review the textbook where it discusses this. To start, A series: R = r+r+r parallel: 1/R = 1/r + 1/r + 1/r
*April 7, 2015*

**grammar**

I agree with (a) I think if it had said each delegate and each alternate, then (b) would be better.
*April 7, 2015*

**math**

you ought to explain what "1 } 10" means.
*April 7, 2015*

**math**

P is the same as if there were a 5-section wheel with just the numbers 1-5.
*April 7, 2015*

**Math**

you mean you can figure out 2*3+5, but you cannot do the same for 1,2,4? Ai caramba!
*April 7, 2015*

**Algebra**

A: LW = √18√24 = √(18*24) = √(2*3^2 * 2^3*3) = √(2^4 3^3) = 12√3 since A = LW, what if you have (L/2)(W/2)?
*April 7, 2015*

**geometry**

without some kind of explanation of the angles and the diagram, I don't think you can get much help here. By the way, ≅ is congruent. Rather than describing the symbol, why not just say congruent? And your opening sentence is bogus, since you don't say what <1...
*April 7, 2015*

**math help**

F is undefined where the denominator is zero #2 ? #3 domain is all reals except for the undefined value(s) #4 y-intercept (at x=0): -6/(0-3) -1 = -6/-3 - 1 = 2-1 = 1 x-intercept (at y=0) -6/(x-3)-1 = 0 -6 - (x-3) = 0 -6-x+3 = 0 x = -3
*April 7, 2015*

**Math**

well, 12^2 = 144, so you want 6x+6 = 12 or 6x+6 = -12
*April 7, 2015*

**Math**

#1 √(x+4)-3 >= 4 √(x+4) >= 7 x+4 >= 49 x >= 53 #2 t = √(d/16), so we want (using t in seconds) √(d/16) > 60 d/16 > 3600 d > 57600
*April 7, 2015*

**Math**

(2w+a)^8 = ... + 16wa^7 + ... (-x+b)^7 = ... - 35x^3b^4 (y-2z)^4 = ... + 24y^2z^2 So, I get -13440wx^3y^2z^2
*April 7, 2015*

**science.......**

(a) 60W * 1 hr = 60 Wh (b) .060 kWh * .1745 $/kWh = 0.01 200kJ/270s = 740W
*April 7, 2015*

**math**

well, how many points in the empty set?
*April 7, 2015*

**UNISA**

to accrue to how much?
*April 7, 2015*

**math**

If I interpreted the rather garbled English, you want x and y where x+y = 44 xy = 1280
*April 7, 2015*

**math**

eliminate z and you have 100-x-y = 200-10x-2y 9x+y = 100 So, you could let x=10, y=10, that would make z=80 Or, you could have x=1,y=91, so z=8 There is no unique solution.
*April 7, 2015*

**algebra**

I think you need some parentheses in that horrid run-on expression. As written it could mean x^2 - 9y^2/xy / 1/y - 3/x = x^2 - 9y/x * y/1 - 3/x = x^2 - 9y^2/x - 3/x = x^2 - 3(3y^2+1)/x There are, of course, many other ways to parse all that stuffed jammed together. Unless ...
*April 7, 2015*

**science 1 question**

ahem. it does not form energy by spinning. It changes electrical energy into kinetic energy (of motion).
*April 6, 2015*

**science 1 question**

do you feel sucked into the fan when you turn it on? Does it feel like when an elevator starts? That's gravitational. Hint: what the heck does a fan do when you turn it on?
*April 6, 2015*

**Math**

well, ya got a table? Maybe these graphs will help you out in determining the transformations required. http://www.wolframalpha.com/input/?i=plot+y%3D3%5Ex%2C+y%3D3%5E%28%E2%88%92%28x%2B1%29%29+%E2%88%922
*April 6, 2015*

**Calculus**

Just curious. How do you get from 2(2)dy/dt+(2)(-1)(-4)+6(-1)^2=0 to 10 dy/dt+8=0 ???
*April 6, 2015*

**Calculus**

Assuming you mean c^2 = x^2 + 98√(x+57) then c^2(4) = 4^2 + 98√61 = 16+98√61 c(4) = 27.95 2c dc/dx = 2x + 49/√(x+57) at x=4, we have 55.90 dc/dx = 8+49/√61 dc/dx = 0.255 Of course, I might have misread the function, with all those pesky words ...
*April 6, 2015*

**Chemistry**

(a) you are diluting the concentration by a factor of 6/.25=24 So, you will need 20/24 ml of 6M solution to produce 20ml of .25M solution. The rest, of course, is water. Do the others in like wise.
*April 6, 2015*

**Calculus**

Hmm. Ignore my previous comment. Still, if the functions are as given, Reiny's answer appears correct. Are there mis-types somewhere?
*April 6, 2015*

**Calculus**

well, what is P? That is the rate you are calculating.
*April 6, 2015*

**1 question omh help??**

Looks like C to me.
*April 6, 2015*

**intermediate algebra**

Hmm. I get (3(x-3) - x(x+3) + 1(x-3)(x-3)) / ((x-3)(x-3)(x+3))
*April 6, 2015*

**Physics**

momentum must be conserved: 1*3 + 2*0 = (1+2)v Although, I fail to see how they could properly roll, if sticking together after such a collision.
*April 6, 2015*

**Physics**

assuming the original mass was really 20.0 kg, total momentum must remain at zero, so 15.0*2 + 5.0v = 0
*April 6, 2015*

**Pre-Calculus**

not quite. since (x+a)^2 = x^2+2ax+a^2, x^2+9x = x^2+9x+(9/2)^2-(9/2)^2 x^2+9x+20 = (x + 9/2)^2 + 20-81/4 = (x + 9/2)^2 + 319/4
*April 6, 2015*

**calc**

f = 2x+15-19e^x f' = 2-19e^x f'(0) = 2-19 = -17 so, the tangent line is y+4 = -17(x-0) see the graphs at http://www.wolframalpha.com/input/?i=plot+y%3D2x%2B15-19e%5Ex%2C+y%3D-17x-4
*April 6, 2015*