Friday
April 18, 2014

Posts by STEVE


Total # Posts: 21,749

Math
that would be (∫[0,8] 5e^-x dx)/(8-0) = 5/8 (1-e^-8)

Algebra
since the denominators are equal, just subtract the numerators: ((5x-2)-(x-2))/(4x) = (4x)/(4x) = 1

trying to understand math
in March, total sales were 9.00 * 125 * 31 = 34875.00 In April, (assuming 30 days, 15 days per half-month) 1st half: 9.00*125 * 15 = 16875.00 2nd half: 11.00*125 * 15 = 20625.00 total: 37500 avg at 11.50 = 43125 so she falls 5625 short. Two items need clarification... There...

math
(pi * .8^2 * .5 m^3) ----------------------- = 32 s (pi * .1^2 * 1 m^3/s)

Algebra
just solve your equation: x^2-81 = 115 x^2 = 196 x = 14 so, the base is 14+9 = 23 height is 14-9 = 5

Algebra
√(5x^2)+7x+2-√(4x^2+7x+18) = x-4 √(5x^2)-√(4x^2+7x+18) = -6x-2 now square both sides to get (5x-2) - 2√(5x^2)(4x^2+7x+18) + (4x^2+7x+18) = (6x+2)^2 4x^2+12x+16 - 2√(20x^4+35x^3+90x^2) = 36x^2 + 24x + 4 √(20x^4+35x^3+90x^2) = -16x^2-6x+...

algebra 1
both correct However, I'd have written #2d as (5x+2 + 3x-1)/2 just to show it's the average of two numbers, rather than half of each.

algebra1
looks like A to me

College Cal 1
if the 2-strand dimension is x, then we have f(x) = 2x + x + 2(15000/x) df/dx = 3 - 30000/x^2 min fence when df/dx = 0, at x = 100 so, the field is 100x150 as usual, the fencing is divided equally among the dimensions. ** f(x) = fencing(x) !

alg
since f(1) = 5, f-1(5) = 1

Algebra
probably not any better than the user's manual that came with it.

Alg.
well, just plug in the values g(-4+h) = (-4+h)^2 - 3 = 13-8h+h^2 g(-4) = (-4)^2 - 3 = 13 so, the numerator is -8h+h^2 divide that by h and you wind up with -8 + h

math
v1 - 3v2 = (1+2j)-3(1+j) = 1+2j-3-3j = -2-j v1*v2 = (1+2j)(1+j) = 1+3j+2j^2 = -1+3j v1*v1 = (1+2j)(1+2j) = -3+4j v1/v2 = (1+2j)/(1+j) * (1-j)/(1-j) = (3+j)/2 you can practice you skills at wolframalpha.com, but use i instead of j.

trigonometry
since 10*468 = 13*360, if we can find all the values of n < 10, then just adding 10 to those values will produce all the possibilities. Finding n<10 should not take too long. For example n=1 works, since 468 = 108(mod 360)

caculus
from the product rule, d(uv) = v du + u dv so, u dv = d(uv) - v du now integrate

MATH HELP
2 kg is about 4.5 pounds So, what do you think?

Calculus Help Please Urgent!!!
Hmmm. we all know that tan x -> x as x->0 so, cot x -> 1/x as x->0 so the limit ought to be zero.

M A T H
no, cost = 4800 + 1400x

Algebra
.04x + .30(200-x) = .08(200) x = 169.2 lbs whole milk so, 30.8 lbs of cream.

Math
Hmmm. we have ∫[0,2] 0.18t^2 + 0.16t + 2.64 = 0.06t^3 + 0.08t^2 + 2.64t [0,2] = .48 + .32 + 5.28 = 6.08 What did you do to arrive at your answer? 1.04 is obviously way off, since f(0) = 2.64 just to start with.

trig/ vectors
he needs to head upstream at an angle θ (measured from the line CD), such that tan θ = 4/12 so, θ = 18.4° The speed required is √(16+144) = 12.65 mph

Math
call the 2 piles x and y P(x) = 3/5 P(y) = 2/(b+2) 3/5 * 2/(b+2) = 6/45 6 / 5(b+2) = 6/45 5(b+2) = 45 b+2 = 9 b = 7

Calc III
well, just plug them in ∂x/∂u = 0 ∂x/∂v = 7 ∂x/∂w = 14w ∂y/∂u = 18u ∂y/∂v = 0 ∂y/∂w = 9 ∂z/∂u = 2 ∂z/∂v = 4v ∂z/∂w = 0 So J = (0 7 14w) (18u 0 9) (2 4v 0) |J| = 1008uvw ...

maths
the area of a sector is 1/2 r^2 θ So, the volume of the cake slice of height h is 1/2 r^2 θh subtract that from the volume of the cake, which is pi r^2 h v = r^2 h (pi-θ/2)

college algebra
If the hole has depth h, then √h/4 + h/1100 = 3.0 h = 132'8"

math trigonometry
if the two towers have heights a and b, then (b-a)/31 = tan 25° a/31 = tan 31° Now just solve for a and b.

math
sinA = 1/2, so tanA = 1/√3 tan(A-B) = (tanA-tanB)/(1+tanAtanB) = (1/√3 - 3/4)/(1+(1/√3)(3/4)) = (25√3 - 48)/39

math
I get AC+B = 3x^^3+14x^2+6x-6 AC has to be 3rd degree, since A is 1 and C is 2 (A+B)(B-C) = -3x^3-5x^2-6x+24 Somewhere you're messing up. Visit calc101.com and click on the "long multiplication" link, and it will show all the details of polynomial multiplication.

math
just substitute in. For example, ABC = (3x+4)(x^2+2)(x^2+3x-2) = 3x^5+13x^4+12x^3+18x^2+12x-16 what do you get for the others?

college algebra
max height when t = 1 h(1) = 576 -16t^2+32t+560 = 0 when t = 7

algebra
recall that lna-lnb = ln a/b, so ln (x+3)/(x-5) = ln 7 (x+3)/(x-5) = 7 x+3 = 7x-35 x = 19/3

algebra
643 e^10k = 813 e^10k = 813/643 = 1.2644 10k = ln 1.2644 = 0.2346 k = 0.02346 now just solve for t in 643 e^0.02346t = 2x10^9

science
well, 1 mole = 22.4 L, so you have 1.15/22.4 moles. that should help.

math
common ratio, so ...

math
identify the sequence 1.6, .8, .4, .2 as arithmetic, geometric, or neither and why.

math
C(g) = 2.19g

math
a gas station charges $2.19 per gallon of gas. use function notation to describe the relationship between the total cost C(g) and the number of gallons purchased g.

math
looks like 8 11 14 17

math
find the 1st 4 numbers of the sequence 3 n + 5

math
625cm/2500cm = 1:4 so, what's 5000/4 ?

Math
since you give no information as to their directions, I will assume they are traveling in opposite directions. So, if the .1kg mass is moving in the + direction, we have 0.1*0.4 - 0.2*1.0 = (0.1+0.2)v v = -8/15

science
why do people have a hard time moving a large rock out of the road

science
what animal would have less momentum then a 52 kg cheetah running at 10 m/s.

science
what is the momentum of a 20kg scooter traveling at 5.o m/s.?

math
this is bogus. Maybe X,Y,Z are all disjoint. So, Z – (X U Y) = Z maybe Z⊆(XUY) so Z – (X U Y) = Ø Looks like you're on your own for this one.

math
well, duh: (2,-3)

Math
w(2w+4) = 400 w = √201 - 1

linear algebra
3/4 as big as or 25% smaller than

Math
assuming you mean a 1 ft cube, then it has 4^3 = 64 smaller cubes. The 8 corners have 3 faces yellow The 12 edges have 2 blocks each with 2 faces yellow, making 24 The 6 faces have a 2x2=4 set of cubes with 1 face yellow, or 24 That leaves the interior 2x2x2=8 cubes all green

Math 10
the graph is a parabola, with vertex at t=1 h(1) = 20 see a picture and analysis at http://www.wolframalpha.com/input/?i=-5t^2+%2B+10t+%2B+15

Math
x+y = 14 30x+60y = 660 6 @ 30" 8 @ 60"

Algebra
w=t+11 2w+t=64 w = 25 t = 14

physics grade 10 icse
v is the same forces in ration 1:2

calculus
Hmmm. If the population is p, then we have dp/dt = kp dp/p = k dt ln(p) = kt + c p = c e^kt Now we know that p triples in 14 days, so we can forgo using e, and just use 3 as our base: p(t) = Po * 3^(t/14) so, starting with 100, and gaining 15 per day and losing 23 each day, ma...

calculus
if the printed area has width and height x and y, then the total area is a = (x+8)(y+12) and xy=384 a = (x+8)(384/x + 12) = 12x + 3072/x + 480 that is minimum when da/dx = 0, so we need 12 - 3072/x^2 = 0 x = 16 so the poster is (16+8) by (24+6) or 24x30

math
a pyramid has a height of 5 inches and a surface area of 90 inches squared. A similar pyramid has a height of 10 inches what is it's surface area?

Math
n(n-1)/2

Algebra
x/(2x-5) - 5/(6x-15) 3x / 3(2x-5) - 5 / 3(2x-5) (3x-5) / 3(2x-5) or 1/2 + 5 / 6(2x-5)

math
I have 7 different pairs of jeans and want to take 2 with me on vacation. how many different ways can you pick 2 pairs of jeans to take on vacation. sorry for not proofing before

math
pairs of jeans and want to take 2 with you. how many different ways can you pick 2 pairs of jeans.

Math
Use partial fractions to see that you have -1/x^2 + 2/x + 3/(x+2) Now it's a piece of cake, right?

math
well, how many numbers are there? 10 how many are divisible by 2? 5

math
you have a spinner labeled 1 through 10. you spin once. what is p (divisimble by 2)

Calculus
y = xe^(-4x) y' = (1-4x)e^(-4x) y" = 8(2x-1)e^(-4x) since e^(-4x) > 0 for all x, y" < 0 when 2x-1 < 0. see the graph at http://www.wolframalpha.com/input/?i=+xe^%28-4x%29+for+0+%3C%3D+x+%3C%3D+1

maths
substitute y=7-2x and you have x^2 - x(7-2x) = 6 x^2 - 7x + 2x^2 - 6 = 0 3x^2 - 7x - 6 = 0 (3x+2)(x-3) = 0 x = 3 or -2/3 so, y = 1 or 25/3

CALCULUS
algebraically, since both functions are symmetric about the origin, the area is zero. geometrically, using symmetry, you have the area is 2∫[0,pi/9] (tan3x - 2sin3x) dx = 2/3 (2cos 3x - log cos 3x)[0,pi/9] = 2/3 (log2 - 1)

CALCULUS PLEASE HELP
seems pretty straightforward. We have ∫[0,10] 2300e^(.024t)-1450e^(.018t) dt = 10107.8 see http://www.wolframalpha.com/input/?i=%E2%88%AB[0%2C10]+2300e^%28.024t%29-1450e^%28.018t%29+dt

CALCULUS
If I read it correctly, you have y=4/x, y=16x, and y=x/16 for x>0 You need to break the area into two regions, because the two top curves intersect at x = 1/2 So the area is ∫[0,1/2] 16x - x/16 dx + ∫[1/2,8] 4/x - x/16 dx = (8x^2-x^2/32)[0,1/2] + (4logx-x^2/32)[...

math
7/10 * 6/9

algebra
(1+.09/12)^(12x) = 500000/25000 x = 33.411 years I figure you can calculate the required day

algebra
just solve for t in (1/2)^(t/5715) = 0.76 t/5715 = log(.76)/log(.5) t = 2262 makes sense, since 76% is about half way to 50%.

math
take a look here: http://www.wolframalpha.com/input/?i=plot+x%2B2y%3D-2%2C+-2x%2By%3D14+%2C+x%3D0%2C+y%3D0

birzit
find t with 5t^2 = 20 then use that t to find the distance d in d = 25t

maths
Since the formula says BAC% = ... I'd say just set it up as 0.1 = (5.14)(4*16*.04) / (.73)(12.5*14) - 0.015H H = 0.2 hours

maths
you have the formula, and you have the numbers. What's the trouble? (aside from converting stones to lbs)

maths
g = 32 ft/s^2 ya just gotta know some things

maths
solve for t in 16t^2 = 5 then plug that t into the distance d = 600t

math
z^2 = -2j = 2cis(3pi/2) z = √2 cis(3pi/4) = √2 (-1/√2 + 1/√2 j) = -1+j

math
1.1c - 150 = 0.6c c = 300

word problem
just solve 34.1 lnx + 117.7 = 250 34.1 lnx = 132.3 lnx = 3.88 x = 48.4 so, we're looking at 2048

Algebra
Hmm. I read it as x(x-7) = 8 Oddly enough, the answer is the same!

finance
(1+r)^4 = 73800/52500 = 1.4057 1+r = 1.0888 r = 8.9%

Finance
(1500(1+.04/4)^(4*5) + 500)(1+.05/4)^(4*5) = 2987.51 2987.51 - (1500+500) = 987.51 330.29 on the 1st deposit 657.22 on the 2nd deposit

math
3/5 x + (1/3)(2/5)x = 110 x = 150 so, he had $40 left.

logarithim
remember that 9^x = (3^2)^x = 3^(2x) so, setting everything to base 3, you have 3^(x-2) = 3^(2(x+4)) now take logs to base 3 on both sides (meaning: if the numbers are equal, then the powers are equal), to get x-2 = 2(x+4) x = -10

algebra
{f,o,d}

algebra
yes. Then since the logs are equal, so are the numbers, and you have (x+3)/(x-5) = 7 x = 19/3

algebra
3ln(4x) = 17 ln(4x) = 17/3 4x = e^(17/3) x = (1/4) e^(17/3)

algebra
3x+2 = 7^5 x = (7^5-2)/3 = 16805/3

algebra Word problem
e^15r = 3 15r = ln3 r = ln3/15 = 7.3%

algebra
since you probably don't have a log base 5 button on your calculator, you need to change base. log5379 = log379 / log5 and on the right, you can use any base you want: e or 10

math
(3.835/100.00)v = 283.79 v = 7400.00 wow - cheap house!

Math HELP
11 cm = .11 m, so now it is 1.6 + .11 = 1.71 m high don't know why you were messing with times tables. They gave you the old height and told you how much it grew. Just add the two numbers!

Math
one week ago was 7 days ago.

algebra
just use the distance formula, which I'm sure you know. The length of the line segment is just the distance between the points: √((0-3)^2+(-6-0)^2) = √(3^2+6^2) = √45 = 3√5

Physics
mv = 7.84*10^7 acceleration from the force is a = F/m = -1.29*10^6/m so, v after force is 7.84*10^7/m - (1.29*10^6/m)(9.65) = 6.6*10^7/m so the final momentum is 6.6*10^7 kg-m/s sorry about using m for mass as well as meters.

Stats.
Wow - you must give up easy. For #a, click the Between button and enter the two values. Then click recalculate. It will show the relevant area and its probability: .0955 If you know the area and want the bounds, then click on the Value from an Area button.

Stats.
a good place for playing around with Z table stuff is http://davidmlane.com/hyperstat/z_table.html

algebra
no reason to estimate, since the quadratic formula provides their exact values. x = (3±√65)/4 since √65 is very close to 8, a good approximation would be x = 11/4 or -5/4

trig
just use your calculator to find the angle with the given property. Then solve for x. For example, tan 58.7° = 1.6443 Since the period of tan(x) is 180°, you have to find x where 90-2x = 58.7: 2x = 31.3, so x = 16 2x = 211, so x = 106 also, continuing on, x = 196,286 D...

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