Mathematics - 4 December 2007

2007-12-04 08:59:05 · 8 answers · asked by AnnaN 1

Can anyone walk me with the follow problem please?

A company can manufacture x items at the cost of c(x) dollars, taken r(x) on these items and realize a profit p(x) = r(x) - c(x) dollars (all amounts in thousands)
Find dc/dt, dr/dt, and dp/dt for the following values of x and dx/dt:

a. r(x) = 70x, c(x) = x^3 - 6x^2 + 45/x and dx/dt = .05 when x=1.5

2007-12-04 08:58:20 · 1 answers · asked by Anonymous

1. Elvin drove halfway from Ashton to Dover at 40 mi/h and the rest of the way at 60 mi/h. What was his average speed for the whole trip? (hint: let the distance for the whole trip be, say, 100 mi.)


2. A train averaged 120 km/h for the first two thirds of a trip and 100 km/h for the whole trip. Find its average speed for the last third of the trip.


3. Pipe A can fill a tank in 5 hours. Pipe B can fill it in 2 hours less time than it takes pipe C, a drainpipe, to empty the tank. With all three pipes open, it takes 3 hours to fill the tank. How long would it take pipe C to empty it?

2007-12-04 08:53:20 · 3 answers · asked by Anonymous

Ariana took 2 h longer to drive 360 mi. on the first day of a trip than she took 270 mi. on the second day. If her speed was the same on both days, what was the driving time each day?

2007-12-04 08:52:19 · 3 answers · asked by God Bless America!~ 4

I just dont know what the a and b are....
help?

2007-12-04 08:49:43 · 3 answers · asked by jo l 1

with two dice

2007-12-04 08:44:54 · 3 answers · asked by Nikhil R 1

Find the length of the chord EF

2007-12-04 08:43:58 · 1 answers · asked by Anonymous

Ok I have a 45-45-90 triangle and I need to find the perimeter of it. I understand that you have to add all of the sides up to get the perimeter,but I need my answer in simple radical form and I dont understand how to add these radicals together. The two legs are radical(2) and the hyp is 2. Plz help!!!

2007-12-04 08:42:48 · 3 answers · asked by lusius188 1

x-(-2x -2) + 3 = 3x+ 9

2007-12-04 08:40:06 · 6 answers · asked by Anonymous

the big numbers are exponents. Thanks

2007-12-04 08:36:51 · 6 answers · asked by Anonymous

Just for fun since I have nothing to do today, I want you to write a system of equations to solve this puzzle, and solve by using substitution.

If four times the larger number is added to two times the smaller number, the result is 14. When the larger number is reduced by two times the smaller number, the difference is 1. What are the numbers?

Good luck. (:

2007-12-04 08:34:27 · 12 answers · asked by rykster22 1

m and n are positive integers, such that n ≤ m. Prove that:
2^n * n! ≤ (m + n)! / (m - n)! ≤ (m^2 + m)^n

Please answer this problem with work and reasoning for what you did.

Thanks!

And does this problem require combinations in order for the inequality to be proved?

2007-12-04 08:30:58 · 2 answers · asked by UnknownD 6

Yes, that's right, you. :D

I would really appreciate it if you could tell me how to do this Algebra problem. Don't just give me the answer, but explain/show your work. I would really appreciate it, and 10 pts. to the fastest best answer!:

(3x + 2)^6

<3

2007-12-04 08:19:35 · 6 answers · asked by isabelle.the.insomniac 2

Can anyone walk me with the follow problem please?

A company can manufacture x items at the cost of c(x) dollars, taken r(x) on these items and realize a profit p(x) = r(x) - c(x) dollars (all amounts in thousands)
Find dc/dt, dr/dt, and dp/dt for the following values of x and dx/dt:

a. r(x) = 9x, c(x) = x^3 - 6x^2 + 15x and dx/dt = .1 when x = 2

2007-12-04 08:15:04 · 2 answers · asked by Anonymous

I got 11 out of 16 questions right in a test. How do I find the percentage I got right? When you answer please show me how you got it. Thanks 4 answering!!

2007-12-04 08:13:21 · 10 answers · asked by *Country Girl* 2

a firm wishes to detemine if there is a linear relationship between the number of TV commercials broadcast and the sales of its product.

the data are as follows:

# commercials (x)
12, 7, 9, 15, 6, 15, 10, 4

sales (y)
9, 7, 12, 13, 8, 11, 7, 6

a) find the equation of the least-squares regression line.
b) approximately how many sales would be predict for 20 tv commercials.

2007-12-04 07:56:43 · 1 answers · asked by Anonymous

2007-12-04 07:47:20 · 3 answers · asked by Anonymous

How do I solve the polynomial inequality?!

(x + 3)(x - 6) < 0

2007-12-04 07:35:46 · 1 answers · asked by Babygurl91 1

Factor completely :
9a^2-100

2007-12-04 07:34:39 · 2 answers · asked by Anonymous

I have 3 questions

-
Multiply out and simpllify
(x+6)(x-3)

-

Question 2.
Factorise x(^2)-16

-
Question 3
Factorise
x(^2)-5x-14

2007-12-04 07:34:14 · 1 answers · asked by Anonymous

How do i calculate the derivative of
d/dx∫sin^2tdt

the top portion of the integral has a 0 and the bottom has an x.


I'd appreciate any help. Thanks.

2007-12-04 07:33:04 · 4 answers · asked by yefimthegreat 1

How do I solve this equation by making an appropriate substitution?!

2x - 2√x - 40 = 0

2007-12-04 07:32:37 · 5 answers · asked by Babygurl91 1

please include some explanation and some steps

2007-12-04 07:30:35 · 5 answers · asked by Anonymous

How do I use the quadratic formula to solve this equation?!

x^2 + 8x + 52 = 0

2007-12-04 07:23:57 · 4 answers · asked by Babygurl91 1

How do I solve the quadratic equation by completing the square?! HELP!

x2 + 6x + 34 = 0

2007-12-04 07:19:18 · 3 answers · asked by Babygurl91 1

2x = 112.5 - 0.5x^2

i know the final answer.. i just need to know how it is done. thanks

2007-12-04 07:14:07 · 9 answers · asked by whoopy_ass 1

2007-12-04 07:11:21 · 4 answers · asked by Anonymous

please help me
i dont understand it

thanks

2007-12-04 07:08:55 · 7 answers · asked by -x-lollie-x- 1

For the floor plans given below, determine whether the side through the points (2, 3) and (11, 6) is perpendicular to the side through the points (2, 3) and (-3, 18).

Floor plans for a building have the four corners of a room located at the points (2, 3), (11, 6), (-3, 18), and (8, 21).

2007-12-04 07:06:19 · 3 answers · asked by Anonymous

2007-12-04 07:03:09 · 4 answers · asked by peace d 1