Thursday

November 27, 2014

November 27, 2014

Total # Posts: 27,037

**math**

Not quite. After 12 minutes he has climbed 12 meters In the 13th minute, he climbs the final 3 meters and is done. Final time is thus 12:45
*November 3, 2014*

**calculus**

since x^2+y^2 = 36 x dx/dt + y dy/dt = 0 since we want dy/dt = -dx/dt, (x-y) dx/dt = 0 true when x=y, as might be expected. Or, when x = 6/√2 All that stuff about 4m and .5 m/s is just noise, unless there are other parts to the problem.
*November 3, 2014*

**Pre calculus**

r = 7/(5+4sinθ) r(5+4sinθ) = 7 5r + 4rsinθ = 7 5r = 7 - 4y 25r^2 = (7-4y)^2 25x^2 + 25y^2 = 49 - 56y + 16y^2 25x^2 + 9y^2 + 56y = 49 25x^2 + 9(y+28/9)^2 = 49 + 9(28/9)^2 25x^2 + 9(y+28/9)^2 = 1225/9 x^2/9 + (y+28/9)^2/25 = (7/9)^2 See http://www.wolframalpha.com...
*November 3, 2014*

**Calculus**

f(x) = 5x√(x+2) is continuous and differentiable on [0,2], so the MVT applies. f(2) = 20 f(0) = 0 So, the slope of the secant is 10 MVT says that f'(c) = 20 somewhere in [0,2] f'(x) = 5(3x+4) / 2√(x+2) f'(c) = 0 if 5(3c+4) / 2√(c+2) = 10 5(3c+4...
*November 3, 2014*

**math**

If the airport is at (0,0) first leg is to (-2.819,1.026) the second leg is on a course of S20°W for a distance of x where 1.026-xcos20° = 0 x = 1.092 So, the 2nd leg is to (-3.192,0)
*November 3, 2014*

**Algebra**

I'm sure that by now you have figured out that I made an error: (u^2+1 - u^2) / u(u-1) 1 / u(u-1) Now set that equal to 1/u 1 / u(u-1) = 1/u 1 = u-1 u = 2 check: 5/2 - 2/1 = 1/2
*November 2, 2014*

**Algebra**

I assume you mean (u^2+1)/(u^2-u) - u/(u-1) Clearly the LCD is u(u-1) (u^2+1 - u(u+1)) / u(u-1) (-u+1) / u(u-1) Now put both sides over the LCD, throw out u=0,1 and set the numerators equal. Then solve for u. What do you get?
*November 2, 2014*

**Algebra**

If the savings account pays x%, then (x+10)/x = 65/15 x = 3 check: .03m = 1500 m = 50000 So, $50K was invested .13(50000) = 6500
*November 2, 2014*

**Algebra 2**

there are 10 digits; only 8 allowed to start, so 8*10^6
*November 2, 2014*

**Algebra check?**

all correct good work. You can also check your answers by typing in the expression at wolframalpha.com
*November 2, 2014*

**Algebra**

If you're trying to find the expression for the area, you have for some reason combined the x^2 and x terms (a no-no). The area is 1/2(2x^2+4x+2)(x^2+3x-4) (x+1)^2 (x+4)(x-1) As you say, not sure which way to go. You have an expression for the area. Was there some other ...
*November 2, 2014*

**algebra**

huh. That's quite a question just to drop in. Have you not studied your algebra text? The basic idea is that if an equation is true, it remains true if you apply identical operations on both sides of the equal sign. The goal is to choose the operations in an order which ...
*November 2, 2014*

**Math**

You are correct to feel ill at ease. You have confused area and perimeter. You want (x+7)(6) = 120
*November 2, 2014*

**algebra**

After x miles, you want 8 - x/30 = 12 - x/18
*November 2, 2014*

**Calculus I**

If by optimal age, you mean producing the maximum offspring, then yes, you want to find where dr/dx = 0 r(x) = log(e^-.1x * 4x^1.5)/x That's kind of messy, and not tractable to algebraic solution. Netter use a graphical or numeric method. Looks like dr/dx=0 at x=1.07875 ...
*November 2, 2014*

**Algebra**

√7 (7-√7) + 9√7 7√7 - √7√7 + 9√7 16√7 - 7
*November 2, 2014*

**Algebra 1B**

You may be more familiar with the term "discriminant." The discriminant is b^2-4ac, the value inside the square root symbol. So, in this case, the surd being considered is the square root of the discriminant.
*November 2, 2014*

**Math (I've been on this problem for 3 hours)**

well, as I recall, the equilibrium price and quantity are where supply equals demand. So, we want 2p-q+10 = (p+q)(q+10)-3642 since q = 2p+10, that means (p+2p+10)(2p+10+10) = 3642 6p^2+80p-3442 = 0 p = 18.195 so, q = 46.390 Check: 2(18.195)-46.390 +10 = 0 (18.195+46.390)(56....
*November 2, 2014*

**Math (I've been on this problem for 3 hours)**

If the supply and demand functions for a commodity are given by 2p - q + 10 = 0 and (p + q)(q + 10) = 3642 respectively, find the equilibrium price and quantity that give market equilibrium. (Round your answers to two decimal places.) Equilibrium price =
*November 2, 2014*

**physics**

then it hits a brick wall, and bursts into flame. How much energy is released by the explosion of the fuel tank?
*November 2, 2014*

**math**

now: w and w+4, area = w(w+4) after growth, we have (w+3)(w+4+3) = w(w+3)+81 w^2+10w+21 = w^2+3w+81 7w = 60 w = 60/7 Now you can figure all the dimensions.
*November 2, 2014*

**Math Please HELP**

If the supply function for a commodity is given by the equation p = q2 + 12q + 700 and the demand function is given by the equation p = 1800 - 10q - q2, find the equilibrium quantity and equilibrium price. (Round your answers to two decimal places.)Thank You so much
*November 2, 2014*

**Algebra 2**

The maximum height of the ball is reached at t=25/32 Plug that in. If it is greater than 17, then I guess it would depend on how far away the wall is.
*November 2, 2014*

**Math**

horizontal travel: x = Vxt = v cos50° = 0.6428v t .6428v t = 20.75 v = 32.2806/t y = Vy t - 16t^2 = 0.7660v t - 16t^2 = 0.7660(32.2806/t)t - 16t^2 = 24.7270 - 16t^2 y=0 when t = 1.243 Vy (1.243) - 16(1.243^2) = 0 Vy = 19.89 SO, y = 19.89t - 16t^2 Now just find the vertex ...
*November 2, 2014*

**calculus**

Hmmm. Consider u^2 = 3x+4, so x = (u^2-4)/3 2u du = 3 dx x+3 = (u^2+5)/3 x^2 = (u^2-4)^2/9 x^2 / (x+3)√(3x+4) dx = 2(u^2-4) / 9(u^2+5) du = (2u^2-26)/9 + 18/(u^2+5) Integrate that to get 2/27 u (u^2-39) + 18/√5 arctan(u/√5) = 2/27 √(3x+4)(3x-35) + 18/&#...
*November 2, 2014*

**MATHS**

9*20 + 3*10 = 180+30 = 210
*November 2, 2014*

**math**

If x liters of water are added, then .10(5) = .04(5+x)
*November 2, 2014*

**Algebra**

If the formula is v = √(h-8) then you are correct: √(203-8) = √195 = 13.96
*November 2, 2014*

**math**

y = 10832.236 x
*November 2, 2014*

**Calculus**

at the moment in question, the rocket is 5 miles from the observer. h/4 = tanθ dh/dt = 4 sec^2θ dθ/dt 6 = 4(5/4)^2 dθ/dt 24/25 = dθ/dt I expect you can deduce the units.
*November 2, 2014*

**Calculus**

well, what is .0588 * 1609^1.25 ?
*November 1, 2014*

**inequality**

70 + .02x < .09x
*November 1, 2014*

**Calculus**

revenue is demand*price r = p(9000-100p) = 9000p - 100p^2 marginal revenue is dr/dp = 9000-200p
*November 1, 2014*

**Algebra**

If x & y = the following table what is the function of x? x = 1,2,3,4 Y = 1,3,5,7
*November 1, 2014*

**Algebra 2**

think back to your algebra I. Where is the vertex of a parabola? remember x = -b/2a ?
*November 1, 2014*

**algebra**

300+280-320 = 260 So, 260 bought both. That means that 280-260=20 buy only DVDs
*November 1, 2014*

**College Intermediate Algebra**

x^2+4x+3
*November 1, 2014*

**college algebra**

(x-3)^2 + 10(x-3) + 24 (x-3+6)(x-3+4) (x+3)(x+1)
*November 1, 2014*

**st xaviers matj**

mark A construct AB Mark circle of radius AB+3, center A construct perpendicular at B where the circle intersects the perpendicular is C. now construct AD and CD
*November 1, 2014*

**Math Help**

#1 d e^(x^2+6) = e^5x x^2+6 = 5x x^2-5x+6 = 0 x = 2,3
*November 1, 2014*

**Math**

(a) 2x+3y = 580 Now you try (b)
*November 1, 2014*

**Calculus**

Of course it will work. Since you're learning about using derivatives to locate extrema, why would you think it would not work? dc/dt = (0.02t - 0.001) e^(-0.05t) since e^(-0.05t) is never zero, you want 0.02t - 0.001 = 0
*November 1, 2014*

**calculus**

v = 4/3 pi r^3 dv/dt = 4 pi r^2 dr/dt so, dr/dt = (dv/dt) / 4pi r^2 a = 4pi r^2 da/dt = 8pi r dr/dt = 8pi r (dv/dt)/4pir^2 = 2/r dv/dt Now plug in your numbers.
*November 1, 2014*

**Math**

f' = 1/x f'(1) = 1 f(1) = 0 So, you have a point (1,0) and a slope (1), so y = x-1 now plug in x = 1.12
*November 1, 2014*

**Math**

The radius of earth is 6371 km We have rθ = 8000, so θ = 8000/6371 = 71.9° Y is at 20.6°E 35.1°S Now, at latitude Ø, the radius of the circle of latitude is r' = r cosØ So, r' = 6371 cos 35.1° = 5210 km At that latitude, 8000km ...
*November 1, 2014*

**MATHS**

2y+3d = 7.5 3y+2d = 8.0 now just solve for y and d.
*November 1, 2014*

**Math**

f(x) = x^20 roots: 0 I think you might want to impose a few more conditions.
*November 1, 2014*

**physics**

(1/2)(1.25)(2^2) + 2.5(t-2) = 1.5t t = 2.5 2.5*1.5 = 3.75 If the 25s/0.38km is supposed to be the answer, I suspect the units have gotten garbled.
*October 31, 2014*

**Math**

since a = 4pi r^2, 4pi r^2 = 100pi r = 5 so, now use your volume formula.
*October 31, 2014*

**Algebra**

a%b = √(a^2+b^2) so, just plug in your numbers: 5%12 = (-5)%(-12) = 13 so, you have (13)%(13) = 13√2
*October 31, 2014*

**Algebra**

f^-1(x) = (x+5)/2 so, you want x where 2x-5 = (x+5)/2 x=5
*October 31, 2014*

**algebra**

N=2√x, O=x^2 So, just work your way out through the parentheses: N(O(N(O(N(O(3)))))) N(O(N(O(N(9))))) N(O(N(O(6)))) ... Or, note that N(O(x)) = 2√(O(x)) = 2√x^2 = 2x So, you have N(O)^3 = 2^3*3 = 24
*October 31, 2014*

**Algebra 2**

w(w+7) = 120 8(15) = 120
*October 31, 2014*

**math**

(-3+10)/(-4+5) = 7/1 = 7 Note that x changed by 1 and y changed by 7.
*October 31, 2014*

**calculus**

hint: find g(0) and g(1) find where g'(s) = 0, then evaluate g there. pick the min and max of those values.
*October 31, 2014*

**Math**

2(w+3w) >= 48 4w >= 24 w >= 6
*October 31, 2014*

**Calculus**

27^(4/3) = 81 y = x^(4/3) dy = (4/3)x^(1/3) dx so, if dx = -0.1 dy = (4/3)(3)(-0.1) = -0.4 So, 26.9^(4/3) ≈ 80.6 In fact 26.9^(4/3) = 80.6002 pretty close, eh?
*October 31, 2014*

**physics**

You lifted it 1.26m (assuming the table is sitting on the floor) so, what?
*October 31, 2014*

**Calculus**

apparently you mean f(x) = ∛x f(125) = 5 f'(x) = 1/3∛x^2 f'(125) = 1/75 So, now you have a point and a slope. The line is y-5 = 1/75 (x-125)
*October 31, 2014*

**algebra**

g(x) has unbalanced parentheses. I will assume you meant g(x) = √f(x) - 2 h(2) = f(g(2)) = f(√(f(2))-2) = f(√(9)-2) = f(3-2) = f(1) = 7 f^-1(x) = (x+5)/2, so we need 2x-5 = (x+5)/2 4x-10 = x+5 3x = 15 x = 5 plug in x=5 for both functions to verify that it is ...
*October 31, 2014*

**Math**

P(n) = 20000(2^n) Let now be when n=0 four years ago, n = -4, so P(-4) = 20000(2^-4) = 20000/16 = 1250 Now do the same for n = -8 and n=2 You don't really need to set n=0. Suppose we started k years ago. That means that now would be P(k). So, 4 years ago would be P(k-4) = ...
*October 31, 2014*

**calculus please help asap**

TFTFT
*October 31, 2014*

**calculus**

at x=0, the slope is 5 SO, near x=0, y=5x is the linear approximation.
*October 31, 2014*

**calculus**

at x=0 the slope is 2/√5 at x=0, y = √5 So, the line there is y = (2/√5)x + √5 http://www.wolframalpha.com/input/?i=plot+y%3D%E2%88%9A%285%2B4x%29%2Cy%3D2%2F%E2%88%9A5+x%2B%E2%88%9A5+for+x+%3D+-2+to+2
*October 31, 2014*

**Calculus**

so, what did you plug in? What was your final answer?
*October 31, 2014*

**Calculus**

df = √3 dx so, plug in dx=.4 to see how much f has increased
*October 31, 2014*

**Calculus**

f(64) = 8 f'(64) = 1/16 so, the line is y-8 = 1/16 (x-64)
*October 31, 2014*

**Calculus**

as usual, sinθ = y/r cosθ = x/r You know x,y,r so get the functions
*October 31, 2014*

**Math Calculous**

No, you want the angle whose sine is .409 Since sin(30°) is 0.5, your angle will be somewhat less than that. Use your calculator. There is probably a 2nd function button, then hit sin. Check whether it is in degrees or radians mode.
*October 31, 2014*

**Math Calculous**

c is correct. Now just find A using sin A = a/c = 13/31.780 once you have A, recall that A+B=90°
*October 31, 2014*

**algbra**

evidently the downstream speed is twice as fast as the upstream speed. So, 14+x = 2(14-x)
*October 31, 2014*

**maths**

If you mean 1/((x+2)(x+3)) - 1/((x-4)(x-5)) that would be ((x-4)(x-5) - (x+2)(x+3)) / ((x+2)(x+3)(x-4)(x-5)) = (14-14x)/((x+2)(x+3)(x-4)(x-5)) = (14-14x)/(x^4-4x^3-19x^2+46x+120) Now sure what you want to do with the other. And try using "-" instead of "_" ...
*October 31, 2014*

**Pre Calculus**

who said anything about sin-1 ?
*October 31, 2014*

**Math**

C=85+15H
*October 31, 2014*

**Solving inequalities**

just start with 1 and 20 1 20 Now try 2: 1 2 10 20 3, no 4? 1 2 4 5 10 20 and that's all! If you go past 4, you just run into factors already generated. In general, if you find all the factor up to √N, you will also have found all the ones greater than √N.
*October 31, 2014*

**Math**

google vector triple product and you will find lots of proofs. One that is relatively straightforward is at http://www.msci.memphis.edu/faculty/dwiggins/files/triplecross.htm You already know that AxB = -BxA, so that will help in the part (b).
*October 31, 2014*

**Calculus**

just evaluate f'(x) at x=25 f'(x) = -5/2 x^(-1/2) + 3/2 x^(1/2) = (-5/2)(1/5) + 3/2 (5) = 7
*October 31, 2014*

**Calculus**

f'(x) = 4x^3-40x f'(-1) = -4+40 = 36 f(-1) = 45 so the line is y-45 = 36(x+1)
*October 31, 2014*

**Calculus**

let u = x^12-2. Then we have h = u^3, so h' = 3u^2 u' = 3(x^12-2)^2 (12x^11) = 36 x^11 (x^12-2)^2
*October 31, 2014*

**trigonometry**

see the related questions below.
*October 31, 2014*

**Algebra**

correct
*October 31, 2014*

**algebra**

bowling alleys: A charges $5 for shoes and $6/game B charges $21 for shoes and $4/game how many games does it take for the day's bowling to be equal at the two alleys?
*October 30, 2014*

**algebra**

x/3 - 8 = 11 x = 57
*October 30, 2014*

**algebra**

2(5+s) = 28 s = 9
*October 30, 2014*

**math**

(1/2)(6/7)(1/3) = 1/7
*October 30, 2014*

**METRO**

6t+18r = 66 4t+7r = 29 t=2 r=3
*October 30, 2014*

**math**

-5x-4
*October 30, 2014*

**algebra**

-5x-4
*October 30, 2014*

**Algebra**

just sub in x+2 for x: f(x+2) = -5(x+2)+6 = -5x-4
*October 30, 2014*

**Math11**

#1 The MVT requires that f(x) be continuous and differentiable. Luckily, all polynomials meet these requirements. f(x) = 5x^2-3x+2 f'(x) = 10x-3 f(0) = 2 f(2) = 16 So, we want c where f'(c) = 7 10x-3 = 6 x = 0.9 The tangent line at x=0.9 is y-3.35 = 7(x-.9) y = 7x-2.95...
*October 30, 2014*

**Math**

Not quite the order is 0.8000000 0.8800000 0.8888888 0.8898989 0.8989898
*October 30, 2014*

**math**

rational zeros (plus or minus) 1,2,3,6,18 By Descartes' Rule of Signs, 1 positive root 2 or 0 negative roots a little synthetic division yields f(x) = (x+1)(x+3)(x-6)
*October 30, 2014*

**Geometry**

some hints to get you going: #1 tan 25° = .466 So, each step is .466 as high as it is wide. #2 tan 36.8° = 3/4 #3 tanθ = 12/15 = 4/5 θ = 38.7° arctan(10/7) = 55°
*October 30, 2014*

**college algebra**

after t minutes, the two isotopes have remaining amounts of 2^(-t/22) and 2^(-t/37) So, after one hour (60 minutes), the ratio of 162Ho/164Ho is just 2^(-60/22) / 2^(-60/37) = 2^(-60/22 + 60/37) = 2^(-450/407) = 2^-1.10565 = 0.465
*October 30, 2014*

**Statistics**

google for the users manual online.
*October 30, 2014*

**Math**

2x^2-14x -16 = 0 (x^2-7x) = 8 (x^2-7x+(7/2)^2) = 8 + (7/2)^2 (x - 7/2)^2 = 32/4 + 49/4 (x - 7/2)^2 = 81/4 x - 7/2 = ±9/2 x = 7/2 ± 9/2 x = -1,8
*October 30, 2014*

**physics**

t = (16.0-6.5)/3.6 = 3.47 seconds
*October 30, 2014*

**math**

is there a maximum speed? Seems like sufficient force could spin it as fast as you want. It's a stationary bike. It does not move!
*October 30, 2014*

**Algebra**

well, you can factor out the 2 and have 2(3x^2+2)(x+2) 3x^2+2 does not factor, since its discriminant is negative. After all, x^2 is always positive, so 3x^2+2 is always positive.
*October 30, 2014*

**Algebra**

both points have the same y-coordinate, so the equation is y = -3 To get that algebraically, note that the slope is 0/1 = 0 So, y = 0x+b y(-4) = -3, so b = -3 y = 0x - 3 or, just y = -3 slope is 3/5 so, use the point-slope form: y+5 = 3/5 (x-1) y = 3/5 x - 28/5 Doing your way...
*October 30, 2014*

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