urgent reply

[mathlover23]

First, THANK YOU for showing your work!!

Second, let's see if we can reduce this to one variable.

. . . .printed area:
. . . .height: h
. . . .width: w
. . . .area: hw = 60

Then h = 60/w.

. . . .paper area:
. . . .height: h + 3
. . . .width: w + 2
. . . .area: (h + 3)(w + 2)

Substituting from the first part, we get:

. . . .(60/w + 3)(w + 2) = A(w) = 60 + 3w + 120/w + 6

Minimize.

Eliz.




----I took your help and it makes sense but when I differentiation the 60 + 3w +120/w + 6 I don't come out with a solid numerical answer for w which I need in order to find h and thus find the minimal dimensions. THANKS AGAIN!

 

[stapel]

Please reply within the original thread. Thank you.

Eliz.

 

[soroban]

Hello, mathlover23!

[quote:23fyhlgk] A(w) = 66 + 3w + 120/w

Minimize.
Eliz.

When I differentiate the 66 + 3w +120/w, I don't come out with a solid numerical answer for w.[/quote:23fyhlgk]
You must be differentiatinig incorrectly.

We have: . A(w) .= .66 + 3w + 120w^-1

Then: . A'(w) .= .3 - 120w^-2 .= .0

Multiply by w²: . 3w² - 120 .= .0 . . ---> . . w .= .√40