Saturday
November 22, 2014

Posts by Steve


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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