Saturday

November 22, 2014

November 22, 2014

Total # Posts: 26,913

**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*

**Algebra**

slope = -3/2 use the point-slope form, then change to slope-intercept: y-7 = -3/2 (x-5) y = -3/2 x + 29/2 The line is vertical, since both points have the same x-coordinate. So, x = -5 Always check for horizontal/vertical lines first.
*October 30, 2014*

**Math help!**

√((4+2)^2+(-6-2)^2) = √(6^2+8^2) = √(36+64) = √100 = 10 Better check your + and - signs
*October 30, 2014*

**Math**

f(t) = 15(t-3)(t-10) Clearly f(t) < 0 on the interval (3,10)
*October 30, 2014*

**math**

f(x) increasing when f'(x) > 0 f'(x) = 4x^3 - 60x^2 + 282x - 414 = 2(x-3)(2x^2-24x+69) The roots are 3,6±√(3/2) = 3.00,4.78,7.22 So, f' > 0 in (3,6-√(3/2) U (6+√(3/2),∞)
*October 30, 2014*

**Pre calc**

500 x 1000 area = x(2000-2x)
*October 30, 2014*

**Trigonometry**

multiply by 1-tanx to get (1-tanx)^2/(1-tan^2 x) = (1-2tanx+tan^2 x)/(1-tan^2 x) = (1+tan^2 x)/(1-tan^2 x) - 2tanx/(1-tan^2 x) = sec^2x/(1-tan^2 x) - tan2x = 1/(cos^2x-sin^2x) - tan2x = 1/cos2x - sin2x/cos2x = (1-sin2x)/cos2x Your carelessness with parentheses threw me off for...
*October 30, 2014*

**Calculus**

see the related questions below; just change the numbers.
*October 30, 2014*

**algebra**

x + 2/3 x + 1/2 x + 1/7 x = 97 97/42 x = 97 x = 42 check: 42 + 28 + 21 + 6 = 97
*October 30, 2014*

**business math**

c/4 - 6
*October 30, 2014*

**statistics**

4% lie 1.75 std below the mean. So, 60000-5000*1.75 = 51250 If the warranty is for 51250, 96% of the tires will exceed that mileage. You can enter your values and play around with Z table stuff at http://davidmlane.com/hyperstat/z_table.html
*October 30, 2014*

**Math**

Draw your Venn diagram of three intersecting circles. 30 in the center part Since 55 are married and have a cell phone, that leaves 25 in the unlabeled intersection of married and cell. Similarly, 5 in the cell-car intersection not already labeled. 25 in the unlabeled part of ...
*October 30, 2014*

**Algebra**

correct
*October 29, 2014*

**Algebra 2**

as with all parabolas, the vertex is at x = -b/2a, in this case t = 3 So, plug that in to get the max height f(t) = 16t(6-t) That will tell you how long it takes to hit the ground (f=0) As usual, the vertex is midway between the roots.
*October 29, 2014*

**math**

d = (135-100)/5 = 7 100+7 = 107
*October 29, 2014*

**AP physics**

we have initial velocity (Vx,Vy) y = Vy t - 4.9t^2 4.8Vy - 4.9*4.8^2 = 0 Vy = 23.52 x = Vx t 52 = Vx * 4.8 Vx = 10.83 So, v^2 = 10.83^2 + 23.52^2 v = 25.90 at an angle θ such that tanθ = Vy/Vx = 23.52/10.83 = 2.17 θ = 65.28° Now you can plug those values ...
*October 29, 2014*

**Math**

what, no calculator? Much faster than posting it here and waiting for a response.
*October 29, 2014*

**Math**

it's not an equation. It's just an expression. Punch in the numbers on your calculator to see its value.
*October 29, 2014*

**math**

leap years have 366 days
*October 29, 2014*

**math**

x = (c-7000)/210 No calculus needed; just algebra I
*October 29, 2014*

**math**

11/24 - 3/8 = 11/24 - 9/24 = 2/24 = 1/12
*October 29, 2014*

**math**

(2/3)(1/3)x = 4 2/9 x = 4 x = 18 check: spent 12 at A leaving 6 spent 2 at B, leaving 4
*October 29, 2014*

**calc**

v = 4/3 pi r^3 dv/dt = 4pi r^2 dr/dt a = 4pi r^2 da/dt = 8pi r dr/dt = 8pi r (dv/dt / (4pi r^2)) Now just plug in dv/dt and r
*October 29, 2014*

**calc**

PV^1.4 = C using the product and chain rules, V^1.4 dP/dt + 1.4PV^.4 dV/dt = 0 now just plug in your numbers
*October 29, 2014*

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