Mathematics - 20 November 2007

The rate of change of the area affected by a culture is determined by the form dA/dt = k (A^1/2) (M - A) where the rate is proportional to the number of cells on the periphery (A^1/2) and the unaffected area (M - A). k is the proportionality constant.

How do you prove that the tissue culture is growing fastest when M/3? 2nd derivative = 0? But it doesn't turn up.

Find A(t) in terms of the initial area Ao = A(0)?

After what time does the tissue reach M/2?

2007-11-20 15:42:06 · 1 answers · asked by maximgubaya 1

how do you find x when Lnx + Ln(x+3)=1 im confuesd i only got up to Lnx(x+3)= 1 thanksss

2007-11-20 15:39:20 · 3 answers · asked by meow 2

2007-11-20 15:28:51 · 4 answers · asked by claudia 2

if 1500$ is invested now at 7% per annum compounded annually. when will it reach $3150?

2007-11-20 15:22:40 · 2 answers · asked by Anonymous

2007-11-20 15:17:23 · 3 answers · asked by Ariel B 1

The question is "Solve the equation 4 sin^2 (x) − 3 = 0."

I got to the point sin(x) = +/- sqr(3)/2
Do I solve for the positive or the negative or both??

2007-11-20 15:14:00 · 8 answers · asked by Matt S 1

The tank of radius A contains water that has a max depth H, volume V of water in the tank is V=(1/3)pi(H^2)(3A-H). Now the tank has radius 16 feet and is being filled at rate of 13.37 ft^3/min. What is the rate when the water is rising at H= 4ft

I know how to do related rates and got almost everything down, but I just don't know how to start this problem

2007-11-20 15:06:59 · 3 answers · asked by ahhhhmath 2

y = ce^-2x + e^-x is solution of equation y' + 2y = e^-x

Find constant c so the solution satifies initial condition y(-2) = 5

2007-11-20 15:00:47 · 4 answers · asked by Gills 1

There are two difficulties I'm having. First, the problem itself:

For the following problem, (a) Find the intervals on which f is increasing or decreasing, and (b) Find the local maximum and minimum values of f.

14. f(x) = cos^2(x) - 2*sin(x), 0 =< x =< 2*pi

I've come up with the following critical points: 0, pi/2, 4 - 5(??), and 2*pi. First of all, I don't know what's up with the 4 - 5 interval, I mostly discovered it by graphing, though I think something led me to examine it initially. It seems to hold the absolute maximum. How would I actually analyze and find information about that interval? Secondly, how does one fully analyze a trigonometric function? I see that they put it on an interval, so I assume that one should just work through cases? Obviously at this point I can't just algebraically solve the equation for zero.

Any help is appreciated! Thanks!

2007-11-20 14:50:45 · 2 answers · asked by oatmealia 2

Hi, my question is:
x 4 (x to the fourth power) - 625
x4-625

I jsut dont get how to factor fully. Thanks.

2007-11-20 14:44:54 · 7 answers · asked by DeMoN 2

or maybe you can tell me?

2007-11-20 14:35:02 · 10 answers · asked by Patrick W 2

how to convert 7 3/4 to a whole number?

2007-11-20 14:34:34 · 10 answers · asked by Anonymous

2007-11-20 14:30:22 · 3 answers · asked by Dalton 1

2007-11-20 14:26:25 · 5 answers · asked by Dalton 1

Says:make a drawing on a cartesian plane
label 20 lines
2 horizontal
2 vertical
one set of perpendicular lines
one set of parallel lines
list the equation of each lines with appropriate number.
Please help me as soon as possible,Urgent.

2007-11-20 14:19:51 · 1 answers · asked by Thandron D 1

2007-11-20 14:15:48 · 5 answers · asked by soccermonster 1

HELP!

2007-11-20 14:06:03 · 4 answers · asked by Ixel 2

2007-11-20 14:03:17 · 1 answers · asked by Brandi D 2

9^x=243

gah its so easy but i 4got how

2007-11-20 14:02:02 · 7 answers · asked by ahhhhhh 1

I need a detailed explanation for this problem because I am studying for my math test tomorrow by practicing with some problems, but I need a little help =]

1. A restaurant sells large and small submarine sandwiches. Rolls for the sandwiches are ordered from a baker. The roll for a large sandwich costs $0.25 and the roll for a small sandwich costs. $0.15. Melissa, the manager of the restaurant, ordered 130 more large rolls than small rolls. What was the greatest number of large rolls Melissa received if she spent less than $63?

2007-11-20 13:52:35 · 4 answers · asked by MissCurious 2

1 day = 10 metric hour
1 metric hour = 10 metric minutes
1 metric minute= 10 metric seconds
1 metric second = 10 metric miniseconds

what time would it be in our system when the metric clock registers

4 metric hours
5 metric minutes
6 metric seconds
7 metric minisecond

2007-11-20 13:51:23 · 2 answers · asked by Anonymous

2007-11-20 13:47:44 · 5 answers · asked by activista 2

y= -5x^2-x+12 for the interval from x= -2 to x=1

answer given is 4

2007-11-20 13:44:39 · 4 answers · asked by Anonymous

2007-11-20 13:42:14 · 38 answers · asked by Kitty 1

2007-11-20 13:38:52 · 4 answers · asked by hashem b 1

Everyone knows that any number raised to the 0 power will equal one. The first person to answer why this is in the form of a mathmatical proof, gets the best answer..
Its fun

2007-11-20 13:36:41 · 9 answers · asked by ? 3

a. 9
b. 6
c. 3
d. 1

2007-11-20 13:32:33 · 6 answers · asked by ableego 7

2007-11-20 13:23:15 · 3 answers · asked by Anonymous

help please with math

2007-11-20 13:17:30 · 4 answers · asked by La ilaha il Allah 2

a friend phones to ask how to solve 6 - 3x = 18.
using only words to describe this prblem. Your answer must be worded sentence one is step one. Sentence two is the second step, etc. Use words like I added, subtracted, multplied , && divided both sides by something.

2007-11-20 13:05:54 · 6 answers · asked by Anonymous