Sunday

October 23, 2016
Total # Posts: 45,195

**math**

depends on how many songs on an album. You appear to have tried to calculate the result for an album of 5 songs. But, your answer is too large. There are 14 songs in total. If there are no duplicates, then once you have chosen the rock and country, there are 12 remaining songs...

*October 14, 2016*

**maths**

I fail to see how a cone of height 21 can be cut into a cone of height 14. Better explain things a bit more.

*October 14, 2016*

**Maths**

type in your equations at wolframalpha.com and it will show the graphs. Rather than just dump a list of similar problems, try posting one. Then, when that is explained, try your hand at others like it. No one likes to be handed a list with "gimme the answers".

*October 14, 2016*

**Maths**

(2,1) I'm sure you can devise others.

*October 14, 2016*

**Algebra**

Come up with some answers we can check, ok?

*October 14, 2016*

**Math**

(2/7 mi) / (4/9 hr) = 18/28 or 9/14 mi/hr

*October 14, 2016*

**Math**

20.00 - 9.50 = ?

*October 14, 2016*

**algebra hrlp**

a square has 4 equal sides. So, divide 8 into 4 equal pieces.

*October 13, 2016*

**algebra**

closed on the left, open on the right Better review what the inequality signs mean...

*October 13, 2016*

**Algebra**

0.04^(3-√(3x+2))=25*5^√(3x+2) Recall that .04 = 1/25 = 5^-2, and 25=5^2 So, now you have 5^(-2(3-√(3x+2)))=5^(2+√(3x+2)) Now take logs base 5 of both sides, and you have -2(3-√(3x+2)) = 2+√(3x+2) -6 + 2√(3x+2) = 2 + √(3x+2) &#...

*October 13, 2016*

**Math**

recall that ixi = -1

*October 13, 2016*

**Algebra 2**

the name substitution tells you how to solve the system. From the first equation, you know that z = 8-x-y Now, substitute that into the other two equations. That gives you -4x+4y+5(8-x-y)=7 2x+2(8-x-y)=4 or, -9x-y = -33 -2y = -12 Now you can see that y=6 Thus, -9x-6=-33, so x...

*October 13, 2016*

**Math**

width: 26 length: 36 26*36/9 = 104 cm^2 per piece Now think of the factors of 104. Make sure they are also factors of 26 and 36.

*October 13, 2016*

**Algerbra**

Assuming you mean the rectangle is inscribed in the circle (all four corners on the circle), the diagonal of the rectangle is the diameter of the circle. So, w^2 + 16^2 = 20^2 (Think of a 3-4-5 right triangle)

*October 13, 2016*

**math**

just add exponents when multiplying and subtract when dividing. So, (7^-64)x(7^-150)/(7^-7)x(7^2) = 7^(-64-150+7-2) = 7^-209 so, t = -209 or, knowing that negative exponents mean that you swap places in the fraction, you have 7^7 / (6^64 * 7^150 * 7^2) = 1/7^209

*October 13, 2016*

**data management**

5*6*2^12 You don't say how many songs are to be used, so after choosing the 1 each of country and rock, there are 12 remaining songs. The power set of 12 elements has 2^12 members.

*October 13, 2016*

**Physics**

every second the velocity decreases by 1.0 m/s. Looks like it will take 1.0 seconds to stop. time = speed/acceleration (m/s) / (m/s^2) = s

*October 13, 2016*

**physics**

ummm. 250 km/hr ...

*October 13, 2016*

**Math**

or, 3640/3250 = 1.12 for a 12% increase looks good.

*October 13, 2016*

**Math**

8 seeds in a row are separated by 7 spaces. 42/7 = 6 inches apart makes no difference how many rows there were.

*October 13, 2016*

**Precalculus**

m = kn^3/g do with that what you will.

*October 13, 2016*

**Physical Science**

An iron fence is left unpainted, and it reacts with the oxygen in the air, forming rust. The formation of rust is an oxidation-reduction reaction, but it is also an example of a(n) _________ reaction My answer is synthesis

*October 13, 2016*

**Algebra**

x + 18 + x = 24

*October 13, 2016*

**Physics**

F = ma, so a = F/m v = at = F/m * t p = mv = Ft

*October 13, 2016*

**Math (Instanttaneous rate of change)**

just do the algebra. At a=3, f(3+h) = (3+h)^2 = 9+6h+h^2 f(3) = 3^2 = 9 subtract and the numerator becomes 6h+h^2 divide that by h and you have 6+h Up to now, no mention of limits is made. It's just straight Algebra I. Now, to get to the magical part: as h->0, (6+h) -&...

*October 13, 2016*

**physics**

the work done is the change in kinetic energy. W = (1/2)(71.6)(11.8^2 - 5.8^2)

*October 13, 2016*

**Math**

so, how did it go?

*October 13, 2016*

**Math**

I find it rather pointless.

*October 13, 2016*

**geometry**

oh, yeah. The angle is not 40°

*October 13, 2016*

**geometry**

If two angles are complementary, they add to 90. if two angles are supplementary, they add to 180. So, if your angle is x, then its supplement is (180-x), and its complement is (90-x). Now you can derive the needed equation and solve it.

*October 13, 2016*

**Math (Algebra)**

come on. If you have to go 30 miles, and you go 15 miles each hour, you must surely see that it will take two hours. If you want to be sure, include the units: (30 mi) / (15 mi/hr) = 30/15 hr = 2 hr (15 mi/hr)/(30mi) = 0.5/hr That means that you cover half the distance per ...

*October 13, 2016*

**Math (Algebra)**

When B left, A was 30 miles ahead. B is going 15 mi/hr faster than A. So, how long does it take to make up the distance?

*October 13, 2016*

**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*