Saturday
October 25, 2014

Posts by STEVE


Total # Posts: 26,094

Physics
yes. Friction is just another force; nothing special about it.
October 6, 2014

College Physics
a = (-284.4 m/s)/1.4s = -203.1 m/s^2 s = Vo t + 1/2 at^2 = 284.4*1.4 - 1/2 (203.1)(1.4^2) = 199.1 m
October 6, 2014

Math
If each member makes x candles, then 40x = 39(x+3) x = 117 So now you can find the total.
October 6, 2014

MATH
d/dx (x^5 + y^8) is indeed 5x^4 + 8y^7 y' Usually this is done in conjunction with implicit derivatives, where you have some equation like x^5 + y^8 = 7 and you wind up with y' = -5x^4/8y^7 which you then have to evaluate at some point. ------------------------------ h...
October 6, 2014

AP Calc
y^2 = x^2 + 4/x 2y y' = 2x - 4/x^2 y' = (2x^3-4)/x^2 * 1/2y = (x^3-2) / x^2y Now as long as y≠0, y'=0 when x=∛2 y(∛2) = ±√(∛4+4/∛2) = ±√(6/∛2) so that's ok. It looks like the only place with ...
October 6, 2014

algebra
Since F=k∆x, F/∆x is constant. So, if the unstretched length is Lo, 8/(76-Lo) = 14/(85-Lo) Lo = 64 cm
October 6, 2014

Pre Calculus
What part of your text's explanation don't you understand? Any explanation we can give here will say basically the same thing.
October 6, 2014

Math
plug in the values graph the function
October 6, 2014

Math
since y = 10/x, the slope of the tangent at (x,y) is -10/x^2 so the normal has slope x^2/10. So, we have a line with slope y/x = (10/x)/(x^2/10) = 100/x^3 so, where does 10/x = 100/x^3? x = √10 So, at (√10,√10), the slope is 1, and the normal line is just y = x
October 6, 2014

Math
Man, you're a better grouper than I am. The 18 made me think of 9*2, so I got x(x-3)^2 = x^3-6x^2+9x hmm. too many x^2, so 2(x-3)^2 = 2x^2-12x+18 aha - (x+2)(x-3)^2
October 6, 2014

Algebra
if a/b = q remainder r, then a = b*q + r Try it with some small numbers: 37/8 = 4R5 4*8+5 = 37
October 6, 2014

Algebra2
just solve the way you do an equation. Apply a step to all parts of the setup: -1 < 3+2x < 11 subtract 3: -4 < 2x < 8 divide by 2 -2 < x < 4 Ta-da! The other is even easier, since each is separate 1-x > -3 1+3 > x 4 > x 5x-1 > 19 5x > 20 x >...
October 6, 2014

Algebra II
We have a winner!
October 6, 2014

Algebra II
4(4x+1)^2 = 4(16x^2+8x+1) Better double-check your answer.
October 6, 2014

Pre Calculus
No, what it says is (x-c) is a factor of f(x). If (x-c) is a factor of f(x), then f(c) = 0 f(-2) = -4(-8)+5(4)+8 = 32+20+8 ≠ 0 So, (x+2) is not a factor of f(x). You can check this out at calc101.com by clicking on the "long division" button and entering your ...
October 6, 2014

Pre Calculus
I think you mis-stated the problem. Better go back and see just what the theorem says.
October 6, 2014

math geometry
As usual, draw a diagram. Half the chord is of length 4. Draw the radius through the chord's center. Now you have a right triangle with leg 4 and hypotenuse 8, which subtends an angle x such that sinx = 1/2 So, x = 30 degrees. The whole chord thus subtends an angle of 60 ...
October 6, 2014

Math
if f(ax) = af(x), f(x) = kx for some k. check: f(ak) = k(ax) = a(kx) = af(x) f(x+y) = k(x+y) = kx+ky = f(x)+f(y) So, since f(1) = pi, f(x) = pi*x f'(-1) = pi In fact, f'(x) = pi for any x.
October 6, 2014

Math- AP Calc
3x+xy+4y=8 3 + y + xy' + 4y' = 0 y'(x+4) = -(y+3) y' = -(y+3)/(x+4) y" = -[(y')(x+4)-(y+3)(1)]/(x+4)^2 = -[-(y+3)/(x+4)*(x+4) - (y+3)]/(x+4)^2 = -(-3-y-y-3)/(x+4)^2 = (2y+6)/(x+4)^2 check: 3x+xy+4y=8 y = (8-3x)/(x+4) y' = -20/(x+4)^2 y" = 40/(...
October 6, 2014

Math Proof
well clearly, since b_n is between 0 and a_n, as a_n->0, so does b_n. Not sure (b) follows. There must be some other conditions on the sequences.
October 6, 2014

word problems
since time = distance/speed, d/(12-2) = d/(12+2) + 1 d = 35 miles check: 35/10 = 3.5 35/14 = 2.5
October 6, 2014

clemson
If each pen is x by y, with the x side parallel to the river, then 6x+4y = 1680 a = 3xy = 3*x(1680-6x)/4 = (2520x-9x^2)/2 This is just a parabola with vertex (hence maximum area) at x = 140 So, each pen is 140 by 210 As usual, the fencing is divided equally between lengths and...
October 6, 2014

Math
not unless i√12 = √12 I think you meant 4±√-12 = 4±i√12 If so, then you are correct
October 6, 2014

Geometry
Now, if you meant to shift it 3 left and 8 down, then (8,3)+(-3,-8) -> (5,-5)
October 6, 2014

Geometry
singular is vertex, not vertice. Grr. (8,3) + (x-11,y-11) -> (x-3,y-8)
October 6, 2014

math
$591.12/72hr = $8.21/hr
October 6, 2014

Algebra
2x + 6/x = 79/5 10x^2 + 30 = 79x 10x^2 - 79x + 30 = 0 (5x-2)(2x-15) = 0 ...
October 6, 2014

Pre-Calc/Trig...
y = (x^2-4x+4) - 5+4 = (x-5)(x+1)
October 6, 2014

math
3(u-2) = 4(u+3) 3u-6 = 4u+12 u = -18 check: -20/-15 = 4/3 yes
October 6, 2014

Math, ASAP Please
Looks like D to me. Sheesh!
October 6, 2014

Calculus
depends on where the man is. If the man's distance is x, and the shadow has length s, then (x+s)/15 = s/6 Now just differentiate and plug in the distance when you finally deign to include it.
October 6, 2014

Timerate problem(calculus)
v = 1/3 pi r^2 (2r) = 2/3 pi r^3 at r=8, dv/dt = 2 pi r^2 dr/dt Now we just have to decide what "at what rate is the increasing" means
October 6, 2014

math
because 1/5 = 5^-1
October 6, 2014

ALGEBRA
It will take x days, where 1/x = 1/10 + 1/12
October 6, 2014

Maths
Apparently the sides are in the ratio b = 3/5 (a+c) c = 1/7 (a+b) a^2 = 144 a,b,c = 12,9,3 so, area = 144+81+9 = 234
October 6, 2014

Maths
If the bottles cost $x each, then 7x + 13.20 = 10x
October 6, 2014

geometry
(40-2*2)(20-2*2) = ?
October 6, 2014

Math
4/7
October 5, 2014

Math
no way to tell. How tall is the human?
October 5, 2014

Algebra
well, just plug in the points: a|1-b|+c = 4 a|3-b|+c = 8 a|8-b|+c = 3 a = -2, b = 17/4, c = 21/2
October 5, 2014

Algebra
a good site for long division is calc101.com Click on the long division button, and you can see all the details.
October 5, 2014

Calculus
As you can see from the graphs at http://www.wolframalpha.com/input/?i=plot+y%3De^%282x%29%2C+y%3D2x you missed the mark. So, let's see what happened. At the point (x,y) on the curve, the slope is 2e^(2x). A line with slope 2e^(2x) through the origin: e^(2x)/x = 2e^(2x) x...
October 5, 2014

math factoring
2x^4+12x^3-18x^2-108x 2x(x^3+6x^2-9x-54) Now use grouping 2x(x^2(x+6)-9(x+6)) 2x(x^2-9)(x+6) 2x(x-3)(x+3)(x+6)
October 5, 2014

Math
g'(x) = f(x^2) + xf'(x^2)(2x) = f(x^2) + 2x^2 f'(x^2) So, at x=2, g'(2) = f(4) + 8f'(4) = 4+8(-3) = -20 g(2) = 2f(4) = 8 So, now we have a point and a slope: L(x) = -20(x-2) + 8 = -20x+48
October 5, 2014

Math
A = 4pi r^2 dA = 8pi r dr Now plug in the numbers. Recall that % error is dA/A * 100
October 5, 2014

math
Hint: The only common divisors of 24 and32 are 2,4,8
October 5, 2014

9th grade algebra
Are you German? What's With All The Capitalization? The lope of the line is (190-120)/2 = 35 y = 50 + 35x
October 5, 2014

Math
at depth y, the radius of the water surface is r = (10/22)x = 5/12 x So, at depth y, the volume of water is v = 1/3 π (5/12 y)^2 = 25/432 π y^2 dv/dt = 25/216 π y dy/dt 30 = 25/216 π (14) dy/dt 30 = 5.08 dy/dt dy/dt = 5.89 ft/min As always, check my math.
October 5, 2014

statistics
Seems to me just like drawing from a pack of cards without replacement. p = 136/500 * 135/499 * 134/498 = 0.0198
October 5, 2014

solve long divison polynomials
A good site for long division is ath calc101.com Just click on the "long division" tab to see all the details, in proper formatting.
October 5, 2014

cobet, maths
Umm, didn't you just say that 33 like both?
October 5, 2014

calculus
First off, I suspect a typo. Why have two y^2 terms? I figure you meant x^2 + 4xy +4y^2=40 Just do things term by term, and don't forget the product rule: 2x + 4y + 4xy' + 8yy' = 0 y'(4x+8y) = -(2x+4y) y' = -1/2 Weird, huh? Not if you note that x^2 + 4xy +...
October 5, 2014

math
Ummm. First off, what do M and O have to do with the length of AB?
October 5, 2014

Math
4x^2+4y^2-8x-20y+13=0 rearrange things a bit and you get 4x^2-8x + 4y^2-20y = -13 4(x^2-2x) + 4(y^2-5y) = -13 Now complete the squares: 4(x^2-2x+1) + 4(y^2-5y+25/4) = -13 + 4(1) + 4(25/4) 4(x-1)^2 + 4(y - 5/2)^2 = 16 (x-1)^2 + (y - 5/2)^2 = 4 Now does it look familiar?
October 5, 2014

Math
what's to solve? You have just defined a function.
October 5, 2014

physics
The situation can be modeled as though the 1st tank were stationary, and the 2nd tank were retreating at 20 m/s. The horizontal and vertical components of the shell's speed at firing are x: 43.4 m/s y: 246.2 m/s So, the height of the shell is h(t) = 246.2t - 4.9t^2 It hits...
October 5, 2014

Algebra
father's age is f. My age is m. (f-4) = 4(m-4) f+m = 53 Now just solve for f and m.
October 5, 2014

Pre-Calc
well, it's just f(x)/g(x) = (1/x)/(x^3) = 1/x^4 And I'm sure you can figure the domain. It's where the denominator is not zero.
October 5, 2014

Math
clearly, it's b and c try dividing out the x^2 factor
October 5, 2014

Calculus
You have ∫√(u^2-a^2) du, so set u = a secθ du = a secθ tanθ u^2-a^2 = a^2 tan^2θ so it becomes ∫ (a tanθ)(a secθ tanθ) dθ = a^2∫secθ tan^2θ dθ = a^2∫sec^3θ - secθ dθ Now, we all...
October 5, 2014

Calculus
well, if y = sin^2(u) y' = 2 sinu cosu u' u' = ln3 3^x y' = 2ln3 3^x sin(3^x) cos(3^x) = ln3 3^x sin(2*3^x) I think you got some of your 3's mixed up as powers of sin. You appear to have taken the derivative of sin^3 (3^x)
October 5, 2014

Algebra 2 (Please, help me!)
Take |x| shrink it horizontally by a factor of 2: |2x| shift it down 3: |2x|-3 Now shrink it vertically by a factor of 4: (|2x|-3)/4 http://www.wolframalpha.com/input/?i=plot+y%3D|x|%2C+y%3D%28|2x|-3%29%2F4
October 4, 2014

Math
Since the border is on both sides, 5 + 2(2 1/4) = 9.5 7 + 2(2 1/4) = 11.5 2(9.5+11.5) = 42
October 4, 2014

Math
X^2+4x=10 x^2+4x+4 = 10+4 (x+2)^2 = 14 x+2 = ±√14 x = -2±√14
October 4, 2014

Math
that will of course be x miles where 100+.60x = 50+.80x
October 4, 2014

algebra
How could a quadratic be anything like a linear function?
October 4, 2014

algebra
You could think of it as a shifted parabola, where 2x+3(x-2)^2 = 3(x-2)^2 + 2(x-2) + 4
October 4, 2014

algebra
Is there a question in there somewhere?
October 4, 2014

Calculus
the indicated line has slope -1. y' = 6x+4 6x+4 = -1 when x = -5/6 y(-5/6) = -5/4 So, the line is y = -(x+5/6) - 5/4 http://www.wolframalpha.com/input/?i=plot+y%3D3x^2%2B4x%2C+y+%3D+-%28x%2B5%2F6%29+-+5%2F4
October 4, 2014

Physics
How long does it take to drop 785m? 4.9t^2 = 785 Then the horizontal distance traveled in that time is 53.5t
October 4, 2014

Algebra
z- 1/5 > 1/4 My answer is z < 9/20
October 4, 2014

Physics
think on it. If the angle of elevation is 0, a = 0 if x = 90 degrees, a = g So, what trig function has its zero at x=0, and its max at x = 90 degrees?
October 4, 2014

Algebra
If m play in marching band, then m+250-130 = 375 m = 255 How did you arrive at 135? I can see 125, but not 135. Anyway, the question was not "how many play only in the marching band?"
October 4, 2014

math
Let x be the number of 10-person increases. So, since revenue is price*people, R(x) = (200+10x)(30-1.50x) That is just a parabola, with its vertex midway between the roots, at x = (-20+20)/2 = 0 That is, max revenue for just 200 people. That is assuming that the price decrease...
October 4, 2014

Algebra
3*85 <= 83+91+x <= 3*90 255 <= 174+x <= 270 81 <= x <= 96
October 4, 2014

Algebra
correct. But I suspect that was not really the question. If the question was asking for P', then that would be {2,4,6,8} When talking about sets, it's better to use the braces; otherwise, you just have a list, not a set.
October 4, 2014

Algebra
Hmmm. You think 5 is a factor of 16? If so, you need to review the term "factor". Better prune your list a bit.
October 4, 2014

AP Statistics
From the Z table, the 10% tail is 1.282 std from the mean. Since the 10% tail is used on both ends, the mean is halfway between where the tails start. That help?
October 4, 2014

algebra
x=1, y=2: x+y=3, 3x+2y=9 (8)(9)(x+y)/(3x+2y) = 24
October 4, 2014

Science
correct again.
October 3, 2014

Physics
Oops -- v = -9.8t
October 3, 2014

Physics
horizontal speed is constant: 30.9/3.03 m/s The vertical speed is v = at = -4.9t The angle x is such that tan(x) = Vy/Vx
October 3, 2014

Physics
the height is h(t) = 20.7t - 4.9t^2 That's just a parabola; the max height is at the vertex. Now just solve for t when h=0. To save yourself some work, the max height is reached at the center of its flight, so you really only need to calculate one of the above answers, ...
October 3, 2014

Science
You are correct.
October 3, 2014

math
6^2 = 36 1+3+5+7+9 = 25 + 4 = 29 2^5 = 32
October 3, 2014

math
200 * 0.1 = ? Ever hear of a calculator?
October 3, 2014

Math
True, but we also have (a+9)(a+16) = a^2 + 25a + 144
October 3, 2014

one last difference (math)
I think you need to reword your question. 1.2 is the fraction less than 1.8 Now, if you want to know how much less than 1.8 1.2 is, then of course that would be 1.8-1.2 = 0.6
October 3, 2014

math
So, did you use the table?
October 3, 2014

math 156
P(1+.04/4)^(4*6) = 35000 Now just solve for P.
October 3, 2014

math
Just match the values in pairs. A. Each pair adds up to 1002 B. Each pair adds up to 100 Now just figure out how many pairs there are.
October 3, 2014

algebra 2
x=9 2x+3y = 30 Now the rest of the questions get easier.
October 3, 2014

pre-calc
Clearly, since we have a semicircle, the width of the rectangle is half the length. So, A = (3x/2)(3x) P = 2(3x/2 + 3x)
October 3, 2014

Physics
If you are not familiar with the equations for trajectories, the wikipedia article for that subject has a good treatment. Just plug in your values for the equation of motion, and crank it out. If you get stuck, come on back with your work so far, and we can give you a nudge in...
October 3, 2014

Math
In that case, review your basic trig functions. cos(x) = 7/21 Now just find x, with that value for cosine.
October 3, 2014

Pre-Calc/Trig...
No idea. But the answer is clearly B, if for no other reason than that x and y have opposite signs on the left.
October 3, 2014

Pre-Calc/Trig...
recall the point-slope form of a line. In this case, y-1 = 3(x-10) Now massage that into one of the choices.
October 3, 2014

houston community college
Since PV=kT, PV/T is constant. So, since P is constant, V/T is constant. That means: 1.4/(27+271) = V/(177+271)
October 3, 2014

Calc
I don't know what the original problem was, but if the doubling time is 24 days, the formula for the amount present after t days is A(t) = Ao * 2^(t/24) Since 2 = e^ln2, that is equivalent to A(t) = Ao * e^(ln2/24 t)
October 3, 2014

AP CALC. AB
f(x) = 3/x f'(x) = -3/x^2 So, we want -3/c^2 = 3(-3/4) c^2 = 4/3 ...
October 3, 2014

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