Question

A poster is to contain 300 (cm square) of printed matter with margins 10cm at the top and bottom and 5cm at each side. Find the overall dimensions if the total area of the poster is minimum.

Answer 1

If the height is y and the width is x, then

a = (x+10)(300/x + 20)

now find da/dx = 0 for minimum area.

Answer 2

I want this solution