Friday
July 3, 2015

Posts by Steve


Total # Posts: 32,079

ALGEBRA
It might be easier to get rid of the fraction. Just multiply through by 2 and you have x^2 - 2x + 10 = 0 Now just apply the quadratic formula.
April 12, 2015

Math help!
let u = x/(1-x). Then you have u^2-u-6=0 (u-3)(u+2) = 0 So, you have x/(1-x) = 3 x = 3-3x x = 3/4 or x/(1-x) = -2 x = -2+2x x = 2
April 12, 2015

Math Word Problem
so, where do you get stuck? Hint: 4 * ab/2 = 2ab
April 12, 2015

Math
recall that the line with slope m through (h,k) is y-k = m(x-h) which you can rearrange into slope-intercept form. For the circle, try rewriting that as x^2-2x + y^2+5y = -5 Now complete the squares x^2-2x+1 + y^2+5y+25/4 = -5 + 1 + 25/4 (x-1)^2 + (y+5/2)^2 = 9/4
April 12, 2015

Algebra
s = rθ, where θ is in radians so, 4*100*pi/180
April 11, 2015

Math
wrong. it is not a function if the same x-value is related to more than one y-value. Draw any graph. If a vertical line intersects the curve in more than one place, it is not a function.
April 11, 2015

Math
4.5/1.1 * 10^1 looks like about 40
April 11, 2015

physics
this should help http://farside.ph.utexas.edu/teaching/302l/lectures/node137.html
April 11, 2015

calculus
just to be precise, h = 1/(pi r^2)
April 11, 2015

calculus
no ideas at all v = pi r^2 h so, h = (1/pi r^2) to find max volume, dv/dt = 2pi r h now plug in the value for h, and solve for dv/dr = 0
April 11, 2015

Math
better start reviewing the trig functions. 10/x = sin 55
April 11, 2015

Math
tan x = 1.5/8.0
April 11, 2015

Math
check the related questions below
April 11, 2015

algebra
x^4y - y^5 y(x^4-y^4) y(x^2-y^2)(x^2+y^2 y(x-y)(x+y)(x^2+y^2)
April 11, 2015

algebra
Hmmm. (2d-f)/3 = (f-3d)/5 5(2d-f) = 3(f-3d) 10d - 5f = 3f - 9d -8f = -19d f = 19/8 d
April 11, 2015

math
this is similar to the one you posted with volumes. What do you think?
April 11, 2015

algebra
x*5 <= 8
April 11, 2015

math
see the related questions below
April 10, 2015

algebra
2|x + 1/3| < 9 |x + 1/3| < 9/2 -9/2 < x + 1/3 < 9/2 -29/6 < x < 25/6 See http://www.wolframalpha.com/input/?i=2%7Cx+%2B+1%2F3%7C+%3C+9
April 10, 2015

Calculus(easy)
f' is the slope of f if f' > 0, then the curve is sloping upward That is, f is increasing So, we need to find where f' > 0 Since (x−3)^4(x+18)^8 is always positive (even powers are never negative) except at x=3 or x=-18 then f' > 0 where (x-5) &...
April 10, 2015

math
since 1/2 is 2(1/4), multiply the top by 2o to get 10/3 x + 1/2 y = 20 Then 1/2 y = 20 - 10/3 x Plug that into the 2nd equation and you have 1/3 x + (20 - 10/3 x) = 5
April 10, 2015

algebra
yes, I can solve it. what did you do to get your answer? I get x = 6 or -4
April 10, 2015

algebra
if the numbers are x,x+1,x+2 then we want x^2 + (x+1)^2 = (x+2)+2 what do you get?
April 10, 2015

algebra
rationals reals
April 10, 2015

geometry
So, did you use congruent corresponding parts AE and CE to show right triangle AED congruent CED ?
April 10, 2015

geometry
I'm sure you can find several versions of this via google.
April 10, 2015

math
the distance z is given by z^2 = 120^2 + 130^2 + 10^2
April 10, 2015

Math
(b) (c) and (f) are all true The question is poorly worded.
April 10, 2015

pre - CALCULUS
so, what is the leading coefficient test? f(x) = x^2 (x+2) if f(x)=0, then you must have either x^2 = 0 or (x+2) = 0 Note that x^2 is always positive. SO, at x=0, the graph touches the x-axis from above, then goes up again at x = -2, f(x) changes sign from - to +, so the graph...
April 10, 2015

Math
P(x) = -x^2+600x-3000 x(t) = 1.5t^2-2t dP/dt = dP/dx * dx/dt = (-2x+600)(3t-2) = (-2(1.5t^2-2t))(3t-2) = -9t^3+18t^2-8t = -2261 or, dP/dt = (-2x+600)(3t-2) = (-119)(19) = -2261
April 10, 2015

pre - CALCULUS
Assuming you mean h(x) = (6x-14)^8 then just make f(x) =x^8 g(x) = 6x-14 that way (f∘g)(x) = f(g(x)) = (g(x))^8 = (6x-14)^8
April 10, 2015

Pre - CALCULUS
you are correct about x = (12+√24)/12 There is also x = (12-√24)/12
April 10, 2015

Pre - CALCULUS
ever hear of the quadratic formula? x = (-12±√(144-120))/(2*6)
April 10, 2015

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

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