course Mth 271
I did this assignment twice. The first time on the first problem I forgot to hit enter response and it took me to the next problem. I did the next problem and when I went into the folder on my hard drive where it stores all of the work it wasn't there. So, I ran the query again and when I finished it wasn't there again. I got the answers correct except on the very first one part b I got a little mixed up but after reading your response I saw where my mistake was. Do you happen to know why it didn't save on my hard drive? I have typed my answers in below. I hope this is acceptable to you. Sorry.
# 4.a.
The program doesn't write anything to the hard drive until you hit Enter Response. Then it writes the contents of both the Question box and the Answer box.
I checked the program and it worked fine on Asst 21; I checked the coding of Asst 21 and it's no different in nature than the coding of any of the other assts. So, while anything can happen, my guess is that you never hit the Enter Answer button.
In any case your responses below will serve just fine for this Query.
dy/dt = dx/dt[x^2 + y^2]
2x(dx/dt) + 2y(dy/dt) = 0
2(3)(8) + 2(4)(dy/dt) = 0
48 + 8(dy/dt) = 0
8(dy/dt) = -48
-48/8-dy/dt=-6
b.
dx/dt = dy/dt[x^2 + y^2]
looks like you got dx/dt and dy/dt reversed; compare with dy/dt = dx/dt[x^2 + y^2] in part a.
2x(dy/dt) + 2y(dx/dt) = 0
2(4)(-2) + 2(3)(dx/dt)=0
-16 + 6(dx/dt) = 0
6(dx/dt) = -16/6
dx/dt = -2.6
This is the one I got mixed up on but after reading your response I see where my mistake was.
#6.
V=4/3pi r^3
dV/dt= 2
r is changing a 2 in / min, so you should have dr/dt = 2.
dV/dt = 4 pi r^2(dr/dt)
This is correct.
Plugging in dr/dt = 2 and r = 6 gives dV/dt = 4 pi (6^2) * 2 = 288 pi = 904 approx.
dr/dt = 2 and r = 24 gives 4 pi (24^2) * 2 = 4 pi (576)(2) = 4608 pi = 14,476 approx
dr/dt=(1/4pi r^2)(dV/dt)
a.
When r=6
dr/dt = 1/4pi(6^2)(2) = 1/288pi = 904.77
b.
When r = 24 inches
1/4pi(24^2)(2) = 1/4608pi = 14,476.45"
end of document
Good job, but see my notes on a couple of details. Let me know if you have questions.