Question

CAN SOMEONE CHECK MY SOLUTION?
This is an optimization Problem..
see attachment below.

Answer 1

@e.mccormick @phi @Hero @Loser66 @agent0smith

Answer 2

the last equation is correct and the answer of the book is correct, too. your calculation is wrong. my TI83 plus said that the solution for that quadratic equation is x = 3.2 and x = -16. so??? check yours, please

Answer 3

ok.. let me try to solve it again..

Answer 4

aahh.. yeah my calculator also got 3.2..
thanks!!

Answer 5

one more thing, how will i set the domain for this?

Answer 6

you mean range?

Answer 7

uhmm.. x values are domain? y-values are range? right? O.o
maybe you have different terms..
well yeah..

Answer 8

hehehe, phi is here, I am free.

Answer 9

you can simplify your last line (divide by 4) to
5x^2 +64x-256= 0

x= (-64 ± 96)/10
the positive root is +3.2

Answer 10

aahh.. ok.. thanks..

how can I set the domain for this problem?

Answer 11

domain is the set of valid x values... how about 0 to 8 ?

Answer 12

yes! got it :)

thanks a lot.. optimization problems always give me a hard time >.<
how can I find the domains of the problem? any advice?
I always made a mistake in finding the limits of a variable..

Answer 13

First, this was a messy calc problem, and you have the main idea..
for the limits on x, I don't know of a rule.

Answer 14

ok, thanks by the way :))