Question

optimization problem! need help

Answer 1

Ok.

Answer 2

@hartnn

Answer 3

@campbell_st

Answer 4

yeah I already know that

Answer 5

i just dont know how to set it up

Answer 6

so far i got c(x)=20x+10(x+2y)

Answer 7

c(x) is the cost

Answer 8

Area of a rectangle is: \(\sf \color{red}{L \times W}\)
and you have only one side of x, so you have: \(\sf \color{blue}{162 = x + 2y}\)

Answer 9

One side is constrained by a brick wall. Right? Consider that when doing this problem.

Answer 10

yes

Answer 11

I would solve for \(\sf \color{blue}{x}\) = \(\sf \color{green}{162-2y}\) and your area: \(\sf \color{red}{xy}\), plug it in and find your derivative.

Answer 12

You have it right so far. Plug in what you have. But make sure you have it in one variable.

Answer 13

what should i plug in?

Answer 14

when i solved it..it was in 2 variables @abb0t

Answer 15

i got 30x+20y

Answer 16

Do as I did up above. Rearrange to get in only terms of y. So you don't get fractions.

Answer 17

y=(x-81)/2?

Answer 18

Yes, you get 30x + 2(10y) = 162

Answer 19

so it is not (x-81)/2?

Answer 20

You get 30x+20y = 162 \(\Rightarrow\) x = ______________

Answer 21

Then plug in that x into area, and take the derivative. Do you get what I am doing, here now?

Answer 22

x=(162-20y)/30

Answer 23

Now, plug it in to the above equation and differentiate.

Answer 24

which one ...y=x-81/2?

Answer 25

162 = xy

Answer 26

You multiplying

Answer 27

i got 4860=162y-20y^2 @abb0t

Answer 28

@nincompoop can you help me?