Friday
May 27, 2016

Posts by Steve

Total # Posts: 40,845

Math
4/35 = .114 = 11.4% However, the sum of your listed colors (and one color is missing and one is duplicated) does not equal 35.
April 27, 2016

prealgebra
If you mean 6P2 (permutations of 6 things, 2 at a time), then yes, the answer is 6*5 = 30
April 27, 2016

prealgebra
could be, depending in the value of P. and what does P2 mean?
April 27, 2016

Trig
since sin^2θ is never more than 1, you need cos^2θ = 0 so, θ = π/2 or 3π/2 or, solving algebraically, sin^2θ = cos^2θ + 1 cos^2θ - sin^2θ = -1 cos(2θ) = -1 θ = π/2 or 3π/2
April 27, 2016

Geometry
2πr(r+h) = 112π 8π(4+h) = 112π 4+h = 14 h = 10
April 27, 2016

algebra
slope = -13 now you can plug that into the point-slope form, using either point.
April 27, 2016

Math
if the length is L, then you know that 1.8L = 18900 so, divide by 1.8 to get L. If the width is in cm, then you will also get L in cm, so divide that by 100 to get L in meters.
April 27, 2016

Math
the area is 18900/100^2 = 1.89m^2 so, the length is 1.89/1.8 m
April 27, 2016

Algebra
2(x + 6x) = 420 x = 30
April 27, 2016

Calculus
just plug and chug f(x) = f(2) + f'(2)(x-2)/1! + ... f(2) = 1/2 f'(2) = -1/x^2 = -1/2^2 = -1/4 f"(2) = 2/x^3 = 1/4 f(3)(2) = -6/x^4 = -3/8 f(4)(2) = 24/x^4 = 3/4 f(x) = 1/2 + (-1/4)(x-2)/1! + (1/4)(x-2)^2/2! + (-3/8)(x-2)^3/3! + (3/4)(x-2)^4/4! + ... = 1/2 - 1/4 (...
April 27, 2016

Calculus
From 0 to π/2, 4cos(x) is above 8-4x/π, so the area would be ∫[0,π/2] (8-4x/π)-4cos(x) dx = 7π/2 - 4 But there is a second symmetric region between π/2 and π, so the area is double that, or 7π-8 see http://www.wolframalpha.com/...
April 27, 2016

algebra
Apparently you mean tn = 75^(5n) = (75^5)^n tn+1 = tn * 75^5
April 27, 2016

Math(Radicals)
2√6 (3√2 - 12) = 6√12 - 24√6 = 12√3 - 24√6
April 27, 2016

maths
come on - you have the formulas. plug in your numbers. We can check your results. and that's alpha, not alpher.
April 27, 2016

Math
log(y+3) = log(x^3/(x-2)) y+3 = x^3/(x-2) y = x^3/(x-2) - 3
April 27, 2016

Logs
assuming base 10, log(3x-13) = log100 - logx log(3x-13) = log(100/x) 3x-13 = 100/x 3x^2 - 13x - 100 = 0 (3x-25)(x+4) = 0 x = 25/3, since x = -4 is not allowed.
April 26, 2016

math
well, the extra 4 balls added 3.160-2.040 = 1.12g Now you know how much each ball weighs, so you can figure the mass of the box.
April 26, 2016

math
Since the tank has a cross-section area of 100π in^2, each in^3 of ball raises the water level by 1/(100π) in. So, figure the volume of the ball and multiply.
April 26, 2016

Arithmetic sequence
so, follow the hint. add them and multiply them.
April 26, 2016

Geometric series
apparently you have a = 1 r = -1/√2 S20 = a(1-r^20)/(1-r) = 1023/(512(2+√2))
April 26, 2016

Pre-Calculus
g(x) has two branches, so g^-1(x) = ±√(x-7) in either case, the domain is all x such that x-7 >= 0 just as the range of g(x) is [7,∞)
April 26, 2016

trig
34 mi/hr * 1hr/60min * 12*5280in/mi * 1rev/(14π in) = 816.33 rev/min
April 26, 2016

math
Reiny did this. See the related questions below.
April 26, 2016

Math
There are lots of solutions, such as 1/2*6+8*5*7/4+3*9 = 100 4/8*6+2*5*7/1+9*3 = 100 8/4*7+6*9*3/2+1*5 = 100
April 26, 2016

Math
42
April 26, 2016

Algebra Help me Please
the y-intercept is the constant term the end behavior is y->∞ or y-> -∞, as with all polynomials. the only other features of interest are the x-intercepts. A little synthetic division will reveal those.
April 26, 2016

math
anyway, since 2/3 of the odd numbers on a regular die are primes, that means that a prime will come up 2/9 of the time.
April 26, 2016

math
since odds come up 1/3 of the time, I guess it depends on how many of the odd faces are primes. You haven't said how many faces are on the die.
April 26, 2016

Logs
since logs are only defined on positive numbers, we need x^2+14x > 0 x(x+14) > 0 You know that this parabola crosses the x-axis at -14 and 0, and since it opens up, it is positive everywhere except between the roots. So, the domain is (-∞,-14)U(0,∞)
April 26, 2016

scte
you forgot the frequency. anyway, once you have that, just plug in v = L di/dt and crank it out.
April 26, 2016

Algebra
2*6 = 12 (total length of pythons) 21-12 = 9 (amount left for the corn snakes) 9/3 = 3 feet per corn snake c = (21-2*6)/3
April 26, 2016

Math/Precal
(9^2x)/(27^x-2)=81^3x-4 since 9 = 3^2 and 27 = 3^3, this is 3^(4x) / 3^(3x-6) = 3^(12x-16) 4x-(3x-6) = 12x-16 x+6 = 12x-16 11x = 22 x = 2 check: 9^4/27^0 = 81^2 yep
April 26, 2016

algebra
if the steamboat's speed is s, then since time=distance/speed, 147/s = 120/(s-9)
April 26, 2016

math
I have no idea how many times she rolled the die to get the 12 twos, but since 2 only comes up on average 1/6 of the time, she can expect about 16 twos in 100 rolls.
April 26, 2016

Math-check my answers!!!
you can easily check your work by typing in your expressions at wolframalpha.com It will show how they can be simplified, and much other information as well.
April 26, 2016

math
0.10 (1+r)^(2016-1948) = 85 (1+r)^68 = 850 1+r = 1.104 r = .104 or 10.4%
April 26, 2016

Math
B = F+6 (B-22)+(F-22) = (B+F)/2 Try that. Your solution indicates that when they last met, they were 6 and 14. But 6+14 is not half the sum of their ages today.
April 26, 2016

Math
Two old friends meet. They hadn't seen each other in 22 years. Betty is 6 years older than France's, but neither is older than 50. The sum of their ages when they met is exactly half of their ages today. How old is Betty? B= F+6 B=50-22 =28 F =50 -22=28 B=28+6=34 Betty...
April 26, 2016

Math
stop guessing, and try the various functions! Just plug in a value for x and see whether the y also matches. -8*2 - 5 = -21 -8*5 - 5 = -45
April 26, 2016

Math
A? c? d? help meh
April 26, 2016

Math
nope. check again.
April 26, 2016

Math
The ordered pairs (2,-21) and (5,-45) are solutions to which of the following equations? y = -8x - 5 y = -8x + 5 <---- my answer y= 8x - 5 y= 8x + 5
April 26, 2016

maths
(2x+y+7) - (x-y) = (x-y)-2 (x-3y)-(2x+y+7) = (x-y)-2 x=2, y=-3 ...
April 26, 2016

maths
n/2 (2*2 + (n-1)(5/4)) = 204 n = 17
April 26, 2016

maths
Figure how many terms there are (n) Sn = n/2 (39+380)
April 26, 2016

maths
clearly the limit is -0.3
April 26, 2016

maths
Tn = 5 + 7(n-1) = 7n-2 S38 = 38/2 (2*5 + 37*7)
April 26, 2016

maths
do you recognize powers of 3?
April 26, 2016

physics
Let the speed of sound be s. Then the time taken for the splash to be heard is 45/s seconds. That means that the stone fell for 3.12 - 45/s seconds. You know that stone fell 45m, so 5(3.12-45/s)^2 = 45 s = 375 m/s not too close to the expected value of 343 m/s...
April 26, 2016

Calc 2
an+1/an = e^-3 (1 + 2/n + 1/n^2) that ratio is less than 1, so the series converges. see http://www.wolframalpha.com/input/?i=sum+n^2%2Fe^%283n%29
April 26, 2016

Math
44 - 0.95 * (54-34) = 25
April 26, 2016

Math
7+9=16 80/16 = 5 7:9 times 5 is 35:45
April 26, 2016

math
well, 3000 ml is 3 liters.
April 26, 2016

math123
42
April 26, 2016

College Algebra
just find t where 15 e^(-0.051t) = 1
April 25, 2016

algrea brs so hard
your parentheses do not balance. is m7 m*7 or m^7 ? if all you want is to expand it, use the distributive property.
April 25, 2016

math
1/3 for each son. if each ate 1/2 of his share, then 1/2 of the pie was eaten, leaving 1/2 uneaten. You can see that the number of slices does not matter here.
April 25, 2016

Maths Urgent please
well, assuming you meant g(x) = (1/16 + x)^(-5/4) g'(x) = (-5/4)(1/16 + x)^(-9/4) using the chain rule for g(x) = u^n and u = (1/16 + x) do that again for g", and evaluate the fractions.
April 25, 2016

Maths Urgent please
so, what do you get for g'(x)?
April 25, 2016

Calculus II
Looks good to me.
April 25, 2016

Calculus
since the radius is 3/4 the height, The volume of the pile is thus v = π/3 r^2 h = π/3 (3h/4)^2 h = 3π/16 h^3 dv/dt = 9π/16 h^2 dh/dt now, plugging in your numbers, at t=3, v = 3/2, so 3π/16 h^3 = 3/2 h = 2/∛π so, 9π/16 4/∛π^...
April 25, 2016

math
huh? How much do you make on regular days? It will be 1.5 times that much.
April 25, 2016

Math
the given line has slope 1/3 so, perpendicular lines will have slope -3 The line you want is thus (using the point-slope form): y+2 = -3(x-6) or, if you prefer, y = -3x + 16
April 25, 2016

Calculus II
no, but x^(4n+2) will work. duh.
April 25, 2016

Calculus II
squaring the entire series would be (sin x)^2, not sin(x^2) Just replace all the x's with x^2. ∑(-1)^n[(x^2)^(2n+1)]/(2n+1)!
April 25, 2016

Length of similar shapes
25/10 = 5/2 all of the other dimensions are multiplied by that same ratio.
April 25, 2016

Calculus
the separation distance z after t hours is found using z^2 = (200t)^2 + (150t)^2 so, find dz/dt when t=2
April 25, 2016

Math
The medians of the triangle all pass through the center of the circle. The medians intersect 2/3 of the way to the opposite side. The altitude of the triangle is also one of the medians, and it has length 10√3. So, r = (2/3)10√3 = 20/√3 For an equilateral ...
April 25, 2016

Roots, complex numbers
huh? negatives are just numbers, like positives. z^5 = -1 = 1 cisπ z = 1^(1/5) cis(π/5) but since cisπ = cis3π = cis5π, etc., to get all the values from 0 to 2π, z = 1 cis(π/5 k) where k = 1,3,5,7,9 Reiny went over this with you. There are 5 ...
April 25, 2016

Math/Precal
sorry. I meant logy(8y-7)
April 25, 2016

Math/Precal
depends on what you mean by "solve" It is log7(8y-7)
April 25, 2016

math
depends on the table.
April 25, 2016

Math
Does 34 mean 3/4? How can Ava give 920 cranes, when she only made 100? anyway, start writing down the amounts, adding and subtracting as required. At the end, subtract Ava's from Brittany's.
April 25, 2016

Math
yep
April 25, 2016

Calculus
v = 4π/3 r^3 dv/dt = 4πr^2 dr/dt Now just plug in your numbers.
April 25, 2016

Calculus
plug and chug x^2+y^2 = 25 2x dx/dt + 2y dy/dt = 0 Now you have x, y, dx/dt, so find dy/dt
April 25, 2016

Calculus
If his distance from the pole is x and the length of the shadow is s, then s/2 = (s+x)/10 1/2 ds/dt = 1/10 (ds/dt + dx/dt) 4 ds/dt = dx/dt So, the length of the shadow is growing 1/4 as fast as the man's speed. But that's not how fast the tip of the shadow is moving. ...
April 25, 2016

PHYSICS! HELIUM BALLON
the balloon weighs 277*9.8 = 2714.6 N add to that the weight of the helium enclosed. (volume * density * 9.8) so, the volume of air displaced must weigh the same amount. Now just plug in the numbers and crank it out.
April 25, 2016

Calculus
see the other problams - they are all the same thing.
April 25, 2016

Calculus
No, they said that the radius is increasing at a constant rate of 2 cm per minute That means dr/dt = 2. dv/dt = 4πr^2 dr/dt da/dt = 8πr dr/dt You have r and dr/dt, so crank it out.
April 25, 2016

Calculus
the separation distance z after t hours is found using z^2 = (200t)^2 + (150t)^2 so, find dz/dt when t=2
April 25, 2016

Trig
for Lions, assuming that all points lie on the curve, k + Asin(0+C) = 1272 k + Asin(2B+C) = 1523 k + Asin(4B+C) = 1152 k + Asin(6B+C) = 891 I'd start by noting that sin(C) = (1272-k)/A Now you can find cos(C) and then use the sum formulas to expand the other sines.
April 25, 2016

O.D.E
If someone can help me with this ODE I would greatly appreciate it. Thank you in advance! ------ Consider the differential equation dx/dt = 1/2x This is a separable O.D.E., so we know how to find all of its solutions: they are of the form x(t) = sqrt(t+c) where C is a constant...
April 25, 2016

CALCULUS
the small tank has a volume of 96π ft^3 its depth decreases at a rate of (1/2)/(16π) = 1/(32π) ft/s So, A: v(t) = 96π - 1/2 t B: duh C: the large tank's area is 4 times as big, so its depth increases 1/4 as fast, or 1/8 ft/s. D: 6/(192π)
April 25, 2016

Brokport
If the amounts invested are x,y,z then they have told us that x+y+z = 180000 .08x + .06y + .09z = 8520 .08x = 6 * .06y I suspect a typo, since even if the whole amount were invested at 6%, the interest would be 10,800. In other words, there's no way to solve these ...
April 25, 2016

Algebra SOLVING LINEAR EQUATIONS AND INEQUALITIES
#1 you can solve for 1/x and 1/y in the usual ways: elimination: double the 1st and subtract 6/x - 4/y = 28 6/x + 3/y = 7 ------------------- 7/y = -21 1/y = -3 then, 1/x = 8/3 or, y = -1/3 and x = 3/8 using substitution, 3/x = 14+2/y 2(14+2/y) + 3/y = 7 28 + 4/y + 3/y = 7 7/y...
April 25, 2016

Math
(2)(33)(19)[2(33)(19)-33-19] (2)(33)(19)[1254-33-19] (2)(33)(19)[1202] 1,507,308
April 25, 2016

geometry
Find the volume in terms of pi of a sphere with a surface area of 9 pi sq ft
April 24, 2016

Math2
f(x) = 3x^2 - 12x + 2 the y-intercept is clearly at 2. x-intercepts? where y=0. Use the quadratic formula to get x = 2±√(10/3)
April 24, 2016

Math
3 : 2 = 1 : 2/3 = 5 : 10/3
April 24, 2016

Algebra
slope = 15/9 = 5/3 y-4 = 5/3 (x-6) y = 5/3 x - 6 The lines are not perpendicular, because the slopes are not negative reciprocals. The line through the points is perpendicular to y = -3/5 x - 6 However, they do both have a y-intercept of -6.
April 24, 2016

Math
using the vertex form, y = a(x-3)^2 - 6 using the point given, 10 = a(-1-3)^2 - 6 10 = 16a-6 a = 1 y = (x-3)^2 - 6 = x^2-6x+3
April 24, 2016

math
clearly getting a 44 (lower than any of her scores so far) will not raise her grade!! Add up the total points she has so far. A "B" average for 7 tests needs at least 80*7 = 560 points. So, how many does she need to get there?
April 24, 2016

Math
The sequence is not geometric! 17111/19 = 900.5789 1539121/17111 = 89.9492 the ratio is not constant. Fix it, find the common ratio r, and then a6 = 19*r^5
April 24, 2016

Calculus quick question pls
huh? huh? How can you say that? x^2 is always positive, right? At least it is never negative. So, x^2+1 is always positive, and always at least 1. So, dividing by x^2+1 will never yield a vertical asymptote.
April 24, 2016

Calculus quick question pls
vertical asymptotes occur when you try to divide by zero. x^2+1 is never zero. You solved for x^2-1 = 0
April 24, 2016

Math
surely you can do the math. ∫[2,3] (3x^2)-(x^4-10x^2+36) dx = ∫[2,3] -x^4 + 13x^2 - 36 dx = -x^5/5 + 13/3 x^3 - 36x [2,3] = (-243/5 + 13*27/3 - 36*3)-(-32/5 + 13/3 * 8 - 36*2) = 62/15 double that for 124/15 Now you need to ask your teacher how 1436/15 can be right...
April 24, 2016

Math
what's the trouble? You are adding up a bunch of thin rectangles, with width dx and height the distance between the curves. The curves intersect at (±2,12) and (±3,27). Since both functions are even, we can use symmetry and use a = 2∫[2,3] (3x^2)-(x^4-...
April 24, 2016

Absolute and relative change
Nope. 1.07x = 16.05 the 16.05 includes the tax, right?
April 24, 2016

math
30P4 = 30*29*28*27
April 24, 2016

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