Tuesday

October 25, 2016
Total # Posts: 45,262

**physics**

final location is 1.5mi south and 2.43mi east. Now just use the Pythagorean Theorem to find the magnitude (the hypotenuse).

*October 13, 2016*

**physics**

recall that v^2 = 2as You have v and s.

*October 13, 2016*

**Algebra**

For #2, I'd say 64 in. Better fix the question if you want an answer... For #3,4, the 1st number is x, the 2nd is y. Which pair fits the equation?

*October 13, 2016*

**Algebra 2**

If the 2nd number is x, then 2x + x + x+4 = 36

*October 13, 2016*

**math**

If the circle has radius r and the small square has side s, then (s/2)^2 + s^2 = r^2 s^2 = 2 so, 1/2 + 2 = r^2 r = √5/2 Now, the larger square has diagonal 2r, so its area is 2r^2 = 2*5/4 = 5/2 wow - much smaller than I expected!

*October 13, 2016*

**math**

I only see the sides of one triangle. The missing side x must obey 9-8 < x < 9+8

*October 13, 2016*

**Math**

just plug in your numbers: v = 1/3 pi r^2 h

*October 13, 2016*

**Math**

oops. That helps with n^2-15n-100 = 0 Your equation has no real solutions, since the discriminant is negative: 225-400 < 0

*October 13, 2016*

**Math**

well, 100 = 20*5

*October 13, 2016*

**Math**

you cannot solve for x and y. The graph is a line. Any point on the line is a solution to the equation. Now, if you want the x- and y-intercepts, read them off the graph.

*October 13, 2016*

**math**

you want to try that again in English?

*October 13, 2016*

**Math**

no way to tell. There are many possible pairs which work: (0,4), (7,6), (14,8), ...

*October 13, 2016*

**math :-(**

Dang - did I really say that? (1,0) in either case!

*October 13, 2016*

**math :-)**

in (r,θ) it is (0,1) in (x,y) it is (1,0)

*October 13, 2016*

**math**

since e=1, it is a parabola, with vertex at (0,1) opening to the left.

*October 13, 2016*

**Math**

x(x+40) + 190 = (x-5)(x+40+10)

*October 13, 2016*

**math**

Think of Cramer's rule. The determinant of the coefficients is D = k^2-1 So, for any k≠1 or -1 there is a unique solution If k=1, we have x + y + 2z =0 x + y + 3z =0 x + y + 4z = 1 since z=0 ans x+y=0 are the only solutions to the first two, but fail on the 3rd, no ...

*October 13, 2016*

**Maths**

6s^2 and 4s^2

*October 13, 2016*

**Maths**

cost: 96/12 * 40 revenue: 93*4 % profit: divide revenue/cost remember that a quotient of 1.23, for example, means 23% profit

*October 13, 2016*

**Geometric progression**

okay okay time for some of your work, please

*October 13, 2016*

**Geometric progression**

again with the > ?

*October 13, 2016*

**Geometric progression**

S12 = 1(1-(1/2)^12)/(1-(1/2))

*October 13, 2016*

**Geometric progression**

clearly, r=3x

*October 13, 2016*

**Geometric progression**

2/(1-r) = 3 Sn = 2(1-r^n)/(1-r)

*October 13, 2016*

**Geometric progression**

not sure what all the > signs mean

*October 13, 2016*

**Geometric progression**

1/(1-r) = 13

*October 13, 2016*

**Geometric progression**

a/(1-r) = 4 a^2/(1-r^2) = 1/3

*October 13, 2016*

**Geometric progression**

a/(1-r) = 32 a+ar = 24

*October 13, 2016*

**Geometric progression**

1 1+11 = 12 1+11+111 = 123 So, for n terms, that ends up with n*10^0 + (n-1)*10 + (n-2)*n^2 see whether you can arrive at the solution here: http://www.wolframalpha.com/input/?i=sum(k%3D0..n-1)+(n-k)*10%5Ek

*October 13, 2016*

**Math**

since 0.54 is a rational number, I assume you mean as a fraction, or a ratio. 0.54 = 54/100

*October 13, 2016*

**maths**

the speed never changes. however, distance = speed * time

*October 13, 2016*

**Maths**

you don't approximate, you estimate. so, the plane was off the ground for the last 500 meters. At that point, it was at a height h, where h/500 = tan40° The plane's ascending distance d is 500/d = cos40°

*October 13, 2016*

**math**

The parts are 5x,x,2x,x where 9x = 340 Good luck with that, if you want whole mangoes. 360 would be better.

*October 13, 2016*

**Basic math**

3^2 + h^2 = 15^2

*October 13, 2016*

**Calculus**

well, since 0.7 < 1, 0.7^-t -> infinity So, all that stuff on the right -> 0, and A(t) -> 25 typical example of logistic growth.

*October 13, 2016*

**Math**

1/42

*October 12, 2016*

**Math**

6 * 5/2 = 15 The actual time of 8 minutes does not matter. If she has 5/2 as much time, she will read 5/2 as many pages. you cannot multiply pages by minutes or seconds. The units do not make sense.

*October 12, 2016*

**math**

4/10 are boys, regardless of how many that is.

*October 12, 2016*

**Algebra**

no, profit margin is the percent of revenue that is profit. You clearly need to review your text on this matter. Surely there is a similar exercise explained there.

*October 12, 2016*

**Algebra**

I would say so. But the profit is 585-500 = 85

*October 12, 2016*

**Algebra**

you keep saying it is an inequality. You need to use the symbols > or >= or < or <= to indicate the kind of inequality.

*October 12, 2016*

**Algebra**

you have given an equation, not an inequality. I suspect there is more to this problem.

*October 12, 2016*

**8th Grade Math**

since y=kx, y/k = k is constant, so you want y such that y/(11 3/4) = (-12 1/2)/50 y = -47/16

*October 12, 2016*

**math**

Assuming that each runner left the starting line at the sound of the buzzer, in 17 seconds, the teacher has run 85 meters. in 14 seconds, Usain has run 147 meters. Now you can figure each runner's speed. The time left to finish is distance/speed. Now you have to add the ...

*October 12, 2016*

**math**

huh? the teacher has run 50 meters left

*October 12, 2016*

**algebra**

find y when x=0 find x when y=0

*October 12, 2016*

**Chemistry**

the volume has increased by a factor of 400/160. So, the concentration has decreased by the same factor. convert grams to moles and then the concentration is moles/L

*October 12, 2016*

**Math**

570/3.8 = ?

*October 12, 2016*

**algebra 1**

If I told you that one piece was 20 inches long, how would you figure out the other piece? Do the same here, but use "m" as the known length.

*October 12, 2016*

**maths @Reiny did it right**

Oops -- I missed the -120.

*October 12, 2016*

**maths**

wow - pretty garbled language. I will assume you meant An a.p. has 15 terms and a common difference of -3. Find the first and last term if its sum is -120 . S15 = 15/2 (2a+14d) 15/2 (2a+14(-3)) = 120 a = 29 a+14d = -13

*October 12, 2016*

**Statistics**

The probability a company will hire a new employee is 0.38. Suppose three companies are randomly selected. (a) Find the probability all three companies will hire a new employee. (b) Find the probability at least one company will hire a new employee. (c) Find the probability ...

*October 12, 2016*

**Pre-calc.**

These interval questions are easy. f(x) is a 8th degree polynomial with positive first coefficient, so its end behavior on both ends is that it rises up to +infinity. So, look at the smallest and largest roots: -6 and 5 f(x) > 0 for x < -6 and x > 5 So, what about in ...

*October 12, 2016*

**Geometry**

the midpoint is just the average of the two endpoints. Play around with a few numbers, and you will see that this is true. Think of it this way. You start at a, and b is halfway to c. That is, (b-a) = (c-b) The midpoint b can then be found: b-a = c-b 2b = a+c b = (a+c)/2 That...

*October 12, 2016*

**Algebra 2**

for a probability table, the sum of all the probabilities must equal 1.0

*October 12, 2016*

**maths**

sorry file://... is only on your computer.

*October 12, 2016*

**Geometric**

the two angles around the bisector are equal.

*October 12, 2016*

**Algebra**

to be sure, 4x24 = 96, but it does not use the distributive property. Unless the original expression was something like 4x(20+4)

*October 12, 2016*

**Math**

.075 = 75/990

*October 12, 2016*

**Mathmatics - ahem**

I get 4x^2 - 7x + 3 = 0

*October 12, 2016*

**calculus**

v = 4/3 pi r^3 dv/dt = 4 pi r^2 dr/dt Now just plug in your numbers and solve for dr/dt.

*October 12, 2016*

**Pre-Calc.**

when Bob starts, Alice is 8 miles ahead. So, how long will it take Bob to catch up, going 2 mi/hr faster than she?

*October 12, 2016*

**Algebra (really need help)**

plug in your numbers here, and see all the details: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

*October 11, 2016*

**pre-calc**

you have to solve 4 problems: (2x+1) >= (x-3) (2x+1) >= -(x-3) -(2x+1) >= (x-3) -(2x+1) >= -(x-3) some may have no solution, since it may not satisfy the initial condition.

*October 11, 2016*

**Precalculus**

you have L. Just plug it in and evaluate T.

*October 11, 2016*

**Math**

you do not want h(0) -- that is the initial height (time t=0) You want t when h=0. That is, -16t^2 + 400 = 0 t^2 = 25 t = 5

*October 11, 2016*

**science/math**

42

*October 11, 2016*

**Math**

5lb/gal * 16oz/lb * 1gal/4qt = 20 oz/qt

*October 11, 2016*

**graphing**

y=2x+3. y(-1) = 2(-1)+2 = -2+3 = 1 y(1) = 2(1)+3 = 2+3 = 5 and so on The line y=6 is a horizontal line. A horizontal line through (3,4) is y=4

*October 11, 2016*

**Algebra**

in no way you cannot just throw away the -3 and the 4. At any rate, if you plug your solutions into the original equations you will see that they do not work at all. The real problem is that you are supposed to find a value for x and y which works in both equations. If you use...

*October 11, 2016*

**lim help**

you know that lim (1 + 1/n)^n = e In fact, lim (1 + 1/(n+k))^n = e (n+4)/(n+1) = 1 + 3/(n+1) so, lim (1 + 3/(n+1)) = e^3 see whether you can justify that

*October 11, 2016*

**Quick Math Help**

these are all just arithmetic sequences. An = a + (n-1)d Sn = n/2 (2a + (n-1)d) see what this gives you

*October 11, 2016*

**mathe**

16/2 (2a+15d) = 240 4/2 (2(a+16d) + 3d) = 220

*October 11, 2016*

**Algebra**

(300/132)*5 - 3

*October 11, 2016*

**Maths**

the amounts are 2x and 5x 7x = 490 so, ...

*October 11, 2016*

**Calculus**

ds/dt = -2/27 t + 2/√t = (54-2t^(3/2))/(27√t) ds/dt=0 when 54 - 2t^(3/2) = 0 t^(3/2) = 27 t = 9 now just find s(9)

*October 11, 2016*

**Maths**

3/4 = 24/32

*October 11, 2016*

**Pre- Algebra**

C and D are correct (almost) any number with an exponent between -7 and 7 will work. I suspect a typo somewhere.

*October 11, 2016*

**maths**

draw a diagram. If the building has height h, and the chopper is x above the building h cot60° = (h+x)cot30° Both of these are equal to the distance of P from the building. Once you have that, you can find h and x. Without knowing that or h, you cannot find x.

*October 11, 2016*

**Calc**

sketch the region. It will be clear that ∫[0,8] ∫[∛y,2] 8e^x^4 dx dy = ∫[0,2] ∫[0,x^3] 8e^x^4 dy dx = ∫[0,2] 8x^3 e^x^4 dx = 2e^x^4 [0,2] = 2(e^16-1) Nice trick, since e^x^4 does not integrate well.

*October 11, 2016*

**Calc**

∫[0,1]∫[√x,1] 8(y^3+1) dy dx = ∫[0,1]8(y^4/4+y)|[√x,1] dx = ∫[0,1]8[(1/4+1)-(x^2/4+√x)] dx = ∫[0,1] -2x^2 - 8√x + 10 dx = (-2/3 x^3 - 16/3x^(3/2) + 10x [0,1] = -2/3 - 16/3 + 10 = 4

*October 11, 2016*

**Calc**

Not sure just what you intended. I (sort of) see ∫[4,12]∫[0,3y] 5e^(x^2) dx dy It seems wrong; maybe you could fix it so it is (a) correct (b) readable

*October 11, 2016*

**Pre Cal**

Using the law of cosines, the distance z is z^2 = (2.5*340)^2 + (2*340)^2 - 2(2.5*340)(2*340)cos(141°) z = 1443 bearing: 90-θ where tanθ = (2*340*cos51°)/(2.5*340+2*340*sin51°) θ = E 17.25° N or 72.75°

*October 11, 2016*

**math**

Let t be the number of years since 1991. Then we have P(t) = 114 * (120/114)^(t/(1997-1991) = 114 * 1.05263^(t/6) Now find P(2014-1991) = P(23)

*October 11, 2016*

**Math**

ok - fix it and go from there.

*October 11, 2016*

**Math**

start with: b/g = 3/5 g = b+20

*October 11, 2016*

**math**

well, what is their greatest common factor? Hint 7 does not divide either 27 or 36. and why did you write each answer twice?

*October 11, 2016*

**Calculus**

do this like the other. Find the xy-plane boundary of the base, and set the height to z = 3x+3y

*October 11, 2016*

**Calculus**

The hypotenuse of the base is the line y = (7-x)/3 So, add up all the small solids with base dx dy and height z v = ∫[1,4]∫[1,(7-x)/3] 7xy dy dx

*October 11, 2016*

**Math - correction**

Not quite. b/g = 3/7 g = b+20 b = g-20 = 7b/3 - 20 4b/3 = 20 b = 15 check: 15/35 = 3/7

*October 11, 2016*

**math**

type it into google - it will calculate for you or (just a thought), use your own calculator! If you want the answer as a fraction, type it in at wolframalpha.com

*October 11, 2016*

**physical science**

velocity is m/s. So, 20m/2.3s = 8.7 m/s

*October 11, 2016*

**physics**

so many unanswered questions. Does the ball roll around inside? Bounce off the ends? Shaken up/down or side-side? Surely there is some further context.

*October 11, 2016*

**science**

R = p * L/A You have the p and A, but the resistance R depends on the length.

*October 11, 2016*

**Math**

not sure what quotientshapes are, but yes, you can get a reasonable approximation by doing 6/31 6/31 = 0.195 5.8/30.8 = 0.188

*October 11, 2016*

**Math**

by 1.30^2 = 1.69 or 69%

*October 11, 2016*

**Math**

a 4x4 square

*October 11, 2016*

**Math (Limits)**

f(x) = 2x^2 − 8x f(x+Δx) = 2(x+Δx)^2 − 8(x+Δx) now just crank it out, as in the examples from your text.

*October 11, 2016*

**math**

the circumference of a circle of radius 4.2

*October 10, 2016*