A page should have perimeter of 42 inches. The printing area within the page would be determined by top and bottom margins of 1 inch from each side, and the left and right margins of 1.5 inches from each side. What should be the overall dimensions of the page in order to maximize the printing area?

Answer 1

length ---- x
width ----- y
2x+2y = 42
x+y = 21
y = 21 - x

printing area:
length = x-2
width = y-3 = 21-x - 3 = 18-x

area
= (x-2)(18-x)
= 18x - x^2 - 36 + 2x
= -x^2 + 20x - 36

since this is a downwards parabola, the vertex will be the answer to your question.
Find the vertex by whatever mean you learned.

Answer 2

tfvhn