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December 21, 2014

Posts by steve


Total # Posts: 27,665

science
s = 1/2 at^2 v = at = √(2as) So, just plug in the numbers to get v.
November 10, 2014

algebra
Note that A(8,12)+(-5,-13) = M(3,-1) Since M is halfway to B, we need to add the same amounts to M that got us there from A: M(3,-1)+(-5,-13) = B(-2,-14)
November 10, 2014

Math please help
Just so you can check your work, you should come up with 1/8
November 10, 2014

math
5.6930 x 10^4
November 10, 2014

pre calc
f(x) = 6x^7 + 7x^6 f'(x) = 42x^6 + 42x^5 = 42x^5(x+1) so, now it's easy to see where f'(x) = 0
November 10, 2014

Math Pre Calc Help
(cos^4x -sin ^4 x)/(sin^2x) (cos^2x-sin^2x)(cos^2x+sin^2x)/sin^2x (cos^2x-sin^2x)(1)/sin^2x cos^2x/sin^2x - sin^2x/sin^2x cot^2x - 1
November 10, 2014

College Math
v0 t - 16t^2 = 0 when t=8, so 8 v0 - 1024 = 0 v0 = 128 Now just find the vertex of the parabola, at t = -b/2a which in this case is at t = v0/32 = 4 that sounds correct, since it is at half the time to hit. 4 sec up, 4 sec down. So, just find s(4)
November 10, 2014

Pre-Calc/Trig
y-intercept is where x=0: f(0) = 0 x-intercept is where y=0 y = x(4-x^2) = x(2-x)(2+x) So, the x-intercepts are at -2,0,+2
November 10, 2014

Math 201 ( Algebra)
If there are x at $40 and y at $80, then 40x+80y = 1000 x = y+80 Now just solve for x and y
November 10, 2014

calculus
if the square has side s and the circle has radius r, then r+s = 360 pi r^2 = (360-r)^2 (pi-1)r^2 + 720r - 129600 = 0 r = 129.85 ...
November 10, 2014

Calculus
y = x^(2/3) * ((5/2)-(x) y' = (2/3)x^(-1/3)*(5/2 - x) + x^(2/3)(-1) = 5(1-x) / (3*x^(1/3)) So, y'=0 when x=1 y" = -5(2x+1) / (9x^(4/3)) y"(1) < 0, so f(1) is a maximum See the graph at http://www.wolframalpha.com/input/?i=+%28x^2%29^%281%2F3%29+*+%28%285%...
November 10, 2014

Calculus angle of elevation with elevator
The two solutions below have exactly the same problem, and each step is shown. Where do you get stuck?
November 10, 2014

Calculus angle of elevation with elevator
see the related questions below - just change the numbers
November 10, 2014

limerick poem
oops - bad closing tag...
November 10, 2014

limerick poem
Just because it has five lines and rhymes, that does not make it a limerick. There is a certain very strict meter which must be followed. Read a bunch of them, then try again. Your meter is way off. The rhythm must be as in There was an old man from Nantucket Who kept all his ...
November 10, 2014

Math! Algebra 1!
If the still-water speed is s, then since distance = speed*time, then in equal time (say, t=1), (s+1.5) = 2(s-1.5) s+1.5 = 2s-3 s = 4.5 100/4.5 = 22.22 hrs or 22 hr 13 min 20 sec
November 10, 2014

Calculus angle of elevation
of course there is... when the elevator is x meters up, tanθ = (x-31)/22 So, sec^2θ dθ/dt = 1/22 dx/dt when x=20, tanθ = -11/22, so sec^2θ = 5/4 5/4 dθ/dt = 1/22 (3) dθ/dt = 55/6 m/s Is one of the steps unclear?
November 10, 2014

Calculus angle of elevation
see the related questions below. The first is the identical problem -- just change the numbers.
November 10, 2014

math
so, OHE = 3HER Sure you didn't leave something out?
November 10, 2014

mathematics
2OR = 2x+5 2OR = HE+5 HE = 2OR-5
November 10, 2014

mathematics - incomplete
can you not tell there is some missing information here?
November 10, 2014

Science
(8m/s)/(3s) = 8/3 m/s^2 (40m/s)/(8s) = 5 m/s^2 which is greater?
November 10, 2014

Algebra
the factors of -7 are -1 and 7 1 and -7 can you pick them so they add up to -6? (x+1)(x-7)
November 10, 2014

math
So, you must want the pair (cosθ,sinθ) which is the point on the unit circle associated with θ. 30: (0.866,0.5) 60: (0.5,0.866)
November 10, 2014

math
ok - I thought that might be it. So, now, what ordered pair did you have in mind? 30 degrees is just an angle. Is there supposed to be an ordered pair associated with an angle?
November 10, 2014

math
eh? Not sure what it is you are asking. ff?
November 10, 2014

geometry - incomplete
so, what is the question, again? You seem to have dropped some data, as well as what it is you are asking.
November 10, 2014

math
just write the data as given: a+b+c+d = 9000 a+c+d = 4b b+d = 4/5 (a+c) The first says that a+c+d = 9000-b using the second, that means that 9000-b = 4b b = 1800 So, now we have a+c+d = 7200 1800+d = 4/5 (a+c) Now we know that a+d = 7200-d, so 1800+d = 4/5 (7200-d) 1800+d = ...
November 10, 2014

math(fractions)
no idea. How long is the Blue Trail?
November 10, 2014

calculus
online, we generally use ^ for powers, and * for multiplication. Why bother changing the way it was posted? And the quotient rule says 5(3x+4)^4(3)(4x+1)^2 - (3x+4)^5(2(4x+1)(4)) ----------------------------------------- (4x+1)^4 (3x+4)^4 (15(4x+1)-8(3x+4...
November 10, 2014

what is the rate of change of the angle of eleva
see related questions below
November 10, 2014

calculus
when the elevator is x meters up, tanθ = (x-20)/20 So, sec^2θ dθ/dt = 1/10 dx/dt when x=10, tanθ = -1/2, so sec^2θ = 5/4 5/4 dθ/dt = 1/10 (5) dθ/dt = 2/5 m/s
November 9, 2014

physics
Look out below!! Was there a question in there somewhere?
November 9, 2014

phyics
If the tug pulls at speed v on a course of θ, then in x-y coordinates, 15 + 9cos60° + 35 sinθ = 0 19.5 + 35 sinθ = 0 sinθ = -0.5571 θ = N 33.9° W Now you can figure part B.
November 9, 2014

Calculus
revenue = price * quantity, so r = x(160-2x) = 160x - 2x^2 max revenue when r'=0, or x = 40 So, just plug that in as needed.
November 9, 2014

Math 112
not so. The value is a non-terminating decimal, so it cannot be written exactly. The calculator just shows the first few digits. The only way to write it exactly is: √3
November 9, 2014

math
14.1√2 = ?
November 9, 2014

College Algebra
27.95 + 0.15m = 45.95 find m
November 9, 2014

Math
how much in taxes? well, duh: 7% .07 * 43.99 = $3.08 so, add the price to the taxes to get the total
November 9, 2014

Algebra
If you mean 2/3y + 5 - 3 - 11/12y then collect like terms: 2/3 y - 11/12 y + 5-3 (2/3 - 11/12)y + 2 (8/12 - 11/12)y + 2 (-3/12)y + 2 -1/4 y + 2
November 9, 2014

ap calc
so, solve the equation for f'. You have 3sinx = -2cosx tanx = -2/3 So, that gives you x for maximum value of f(x). Just plug it in and evaluate f(x). Of course, you need to recall how to take sin(arctan(x)) and cos(arctan(x)) But that's just trig, right? Or, note that ...
November 9, 2014

Can you check my answer - Physics
clearly the net force is the sum of the downward and upward forces: -1.5N + 0.7N = -0.8N That is, 0.8N downward You just added the magnitudes, but did not take into account the directions
November 9, 2014

math
Not sure what your characters are, but (A∩B)∪C = {9,10}∪{11,13,15} = {9,10,11,13,15} (A∪B)∩C = {9,10,11,12,13,14}∩{11,13,15} = {11,13}
November 9, 2014

ap calc
f(x) = bx^2+6x if x <= 2 ax^3 if x>2 So, we have lim(x->2-) f(x) = 4b+12 lim(x->2+) f(x) = 8a That means we need 4b+12 = 8a Also, we need the derivatives to be equal: 2bx+6 -> 4b+6 3ax^2 -> 12a And they need to be equal: 4b+6 = 12a rearranging things a bit, ...
November 9, 2014

Math
Since y = kx, y/x = k That is, pick any two known values of x and y. Their ratio is the constant k.
November 9, 2014

College algebra
f(x) has 3 changes, so 3 or 1 + roots f(-x) has no sign changes, so no - roots check: http://www.wolframalpha.com/input/?i=6x^5-6x^4%2B7x^3-8
November 9, 2014

consumer math
799.99(1-0.40) = 479.99 or, $480
November 9, 2014

calculus
y = log |2-x| y' = 1/|2-x| (-1) = 1/(x-2)
November 9, 2014

Pre-trig/Calc
1 positive, 2 or 0 negative check: http://www.wolframalpha.com/input/?i=x^3%2B3x^2-18x-40
November 9, 2014

Math
start with x. The value after each step is listed below x 2x 2x+6 (2x+6)/2 = x+3 x+3-3 = x you always get your original number.
November 9, 2014

calculus
s = t^9 ln|t| s' = 9t^8 ln|t| + t^9/t = t^8(9ln|t| + 1)
November 9, 2014

Math
15.3g + 2q + 3.79 Note that you don't need an equation, just an expression
November 9, 2014

calculus
y' = (26x^2-26)e^-3x - 3(13x^2-26x+26)e^-3x = -13(3x^2-8x+8)e^-3x
November 9, 2014

Math
#1 False A triangle has three angles, which add up to 180 degrees. The two right angles use all that up. #2 True #3 True #4 False Just draw any obtuse triangle. If two of the legs happen to be equal, stretch one of them a little. #5 True #6 False. Draw a tall skinny isosceles ...
November 9, 2014

Math -word problem
Consider the room. The front wall is square ABCD, and the back wall is EFGH. The front outlet (P) is a foot from the floor (AB), and the back outlet (Q) is a foot from the ceiling (GH). A line directly up and across and down is 20 feet. But, you can do the following: Unfold ...
November 9, 2014

calculus
just use the product rule and chain rule: y = uv y' = u'v + uv' where u=(2x+1)^3 v=(4x+1)^-4 y' = 3(2x+1)^2(2)*(4x+1)^-4 + (2x+1)^3*(-4)(4x+1)^-5(4) = -2(2x+1)^2(4x+5) --------------------- (4x+1)^5
November 9, 2014

math pre algebra
how about 5x+7y
November 9, 2014

Algebra 2
plug in your coefficients at http://www.gregthatcher.com/Mathematics/GaussJordan.aspx to see all the details Or, you can try this: http://www.wolframalpha.com/input/?i=solve+{{3%2C4%2C1}%2C{1%2C3%2C-2}%2C{-2%2C1%2C-2}}*{{x}%2C{y}%2C{z}}%3D{{1}%2C{-2}%2C{-5}}
November 9, 2014

Algebra 2
(2x-1)^2 = x^2 + 33 4x^2-4x+1 = x^2+33 3x^2-4x-32 = 0 (3x+8)(x-4) = 0 ...
November 9, 2014

math
315 = 3^2 5 7 882 = 2 3^2 7^2 So, GCF = 3^2 7 = 63
November 9, 2014

math count warm up
just start writing down the facts. If the 4 digits, left to right are a,b,c,d, then: a+b=c b+c=d c+d=10a+b a+b=c d-b=c 10a+b-d=c a+b=d-b a+2b = d 10a+b-(a+2b) = a+b 8a = 2b b = 4a so, c=5a and, d=9a Since a,b,c,d are single digits, a must be 1. So, we get 1459
November 9, 2014

algebra
w(3w-2) = 16 w = 8/3 p = 2(8/3 + 6) = ?
November 9, 2014

math
6 - 4(2/3) = ?
November 9, 2014

projectives
time to hit: 4.9t^2 = 90 t = 4.29 s 4.29s * 50 m/s = 214.28 m
November 9, 2014

calculus
see related questions below
November 9, 2014

Math
Drop a perpendicular from G on CD to F. Now you have a rectangle GDEF with sides 3.5 and 4.5 Also, triangle CGF where CG = 3.5/√3 CF = 7.0/√3 Now the perimeter is easy - add up three sides of the rectangle, and the triangle.
November 8, 2014

math
I don't see any fractions If you meant (11+x)/(13+x) = 10/11 then x=9
November 8, 2014

Calculus
Do you mean ln√x or √lnx ?
November 8, 2014

trig
recall your sum of angles formula for tan recall that tan(180) = 0
November 8, 2014

Math Question
QR = 7.1 tan58° Area = (1/2)(PR)(QR)
November 8, 2014

math
your math is ok, freddy, but the spelling, not so much...
November 8, 2014

math
Hmmm. How can someone savvy enough to use a computer, not know what 1+1 is? I suspect either a test posting, or someone really bored.
November 8, 2014

Algebra 2
You always want to set things equal to zero: 6x^2-13x+6 = 0 Now, just have to have some practice factoring to get to (3x-2)(2x-3) = 0 Now, since if the product of two numbers is zero, one of the numbers must be zero. So, either 3x-2 = 0 and x = 2/3 or 2x-3 = 0 and x = 3/2 You ...
November 8, 2014

Calculus (math)
Draw a diagram, looking from the side. If the observer is at distance x, then The angle Ø from the eye to the bottom of the picture is such that tanØ = d/x The angle θ subtending the picture is tan(Ø+θ) = (d+h)/x We want to determine x for ...
November 8, 2014

math
(3x-2)/8 + (2-x)/ 4 = - 1/2 easy way: clear fractions by multiplying by 8: (3x-2) + 2(2-x) = (-1/2)(4) 3x-2+4-2x = -2 x+2 = -2 x = -6 check: (3(-6)-2)/8 + (2-(-6))/4 = -20/8 + 8/4 = -5/2 + 2 = -1/2
November 8, 2014

mathematics
a + a+2d = 12 (a)(a+d) = 24 a=4, d=2 check: 4,6,8,10,... 4+8=12 4*6=24
November 8, 2014

Mustapha
ever try google? Here's one discussion: http://www.meritnation.com/ask-answer/question/determine-the-oxidation-number-of-cr-in-k2cr2o7/redox-reactions/1515787
November 8, 2014

algebra
#1 If you mean f(n) = 3(n-3) then f(5) = 3(5-3) = 6 f(n) = 3^(n-3) then f(5) = 3^2 = 9 f(n) = 3^n - 3 then f(5) = 3^5-3 = 240 How did you come up with 279? #2 f(n) = 2f(n-1)+2 f(1) = 4 f(2) = 2(4)+2 = 10 f(3) = 2(10)+2 = 22 #3 f(n) = (4-n)/(n+3) f(3) = (4-3)/(3+3) = 1/6 #4 I ...
November 8, 2014

Maths
C = pi * d so, the turns is 44/C where C is in meters
November 8, 2014

math - typo
3:1:15 requires three quantities.
November 8, 2014

calculus
d/dx u^n = nu^(n-1) u' d/dx arctan(u) = 1/(1+u^2) u' d/dx ln(u) = 1/u u' So, we have y' = 2(3/2) √(22x+31) * (22) + 1/(1+(22x+21)) * (1/2) * 1/√(22x+21) * 22 + 1/(11x+16) * 11 - 22 = 66/√(22x+31) + 11/((22x+22)√(22x+21)) + 11/(11x+16) - 22
November 8, 2014

calculus
That would be 4(cos(6x-1) - 6xsin(6x-1)) ------------------------------ 3cos(3x) - 3 at x=0 that is 4(cos(-1)-0) ---------------- 3-3 -> -∞
November 8, 2014

Calculus
See the related questions below
November 8, 2014

Trig
Extend AB to meet the vertical from C at D. It is easy to determine that in triangle ABC ∠C = 47° ∠B = 88° Now just use the law of sines to get AB.
November 8, 2014

Intermediate Algebra
well, let's just assume that there is a t. After all, if there is none, the B is just a constant: 604.47 So, since polynomials are normally written in descending power order, I'd guess B = 18.75t + 585.72 So, you want to solve 18.75t + 585.72 > 1050 18.75t > 464....
November 8, 2014

Intermediate Algebra
B=18.75+585.72 where is the t?
November 8, 2014

Calculus (math)
See the related questions below
November 8, 2014

Math
cos is negative in QII, QIII You reference angle is 0.927 So, x = pi±0.927
November 8, 2014

calculus
V = IR dV/dt = R dI/dt + I dR/dt Now just plug in your numbers.
November 8, 2014

Calculus
I guess you should have checked my math. The actual formula for the volume is (π/3)((18+y)(3+y/6)^2-18*3^2) = π(y^3/108 + y^2/2 + 9y) because the water is in the bottom of the cone dv/dt = π/36(y+18)^2 dy/dt 4.9 = π/36*20^2 dy/dt dy/dt = .14 m/min or 14.0 ...
November 7, 2014

Calculus
When the water has depth y, the radius of the surface is 3 + (y/12)(5-3) = 3 + y/6 Its volume at that point is v = 1/3 (R^2-r^2) h = (1/3)((3+y/6)^2-3^2)y = y^3/108 + y^2/3 Now we are ready to begin. When y=2, v = 8/108 + 4/3 = 38/27 dv/dt = (y^2/36 + 2y/3) dy/dt 4.9 = (4/36...
November 7, 2014

Calculus (math)
as usual, draw a diagram. The distance z between the boats at time t hrs after 2:00 is z^2 = (15t)^2 + (20-20t)^2 2z dz/dt = 2(15t)(15) + 2(20-20t)(-20) z dz/dt = 1250t - 800 clearly dz/dt=0 when t=8/1250 hours Now just change that to a time of day.
November 7, 2014

AP CALC. AB
the .75 comes from the fact that the diameter is increasing 1t 1.5in/min. The radius is half that. and yes, he meant to solve for dh/dt, since that was the question asked. Part 1 just uses the fact that the volume of a box is length*width*height. can you say duh?
November 7, 2014

helpppppppp
7c+3d = 4m 1m = 1c+1d So, 4m = 4c+4d 7c+3d = 4c+4d 3c = d
November 7, 2014

BRAINMATH
If the family has b boys and g girls, b = g+4 So, b = (g-1)+5 so, each sister has 5 more brothers than sisters
November 7, 2014

Pre-Calc/Trig
numerator will be 1 or 2 denominator will be 1 or 3 all can be positive or negative
November 7, 2014

Math
cos pi/3 = 1/2 so, t = pi/3 That's the reference angle. cos is positive in QI and QIV, so the other solution is t = 2pi - pi/3
November 7, 2014

Physics
the vertical speed is 200 sin30 = 100 m/s So, the height is h(t) = 100t - 4.9t^2 As you recall from algebra I, the vertex of the parabola is at t = -b/2a, which in this case is 100/9.8 So, plug that in to get the max height. The ball is in the air twice that long, and you know...
November 7, 2014

Algebra
I'll do one, and you try the other. 2x^2+7x = 4 (x^2 + 7/2 x) = 2 (x^2 + 7/2 x + (7/4)^2) = 2 + (7/4)^2 (x + 7/4)^2 = 81/16 x + 7/4 = ±9/4 x = -7/4 ± 9/4 x = -4 or 1/2 Just recall that (x+a)^2 = x^2 + 2ax + a^2 That's why I added (7/4)^2 to both sides. ...
November 7, 2014

science Help 911!!
Looks good to me.
November 7, 2014

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