a page is to contain 30 square inches of print. the margins at the top and bottom are each 2 inches wide. the margin on each side are only 1 inch wide. find the dimensions of the page so that the least paper is used

1 answer

If the print is x by y, then the page is (x+2)(y+4)

Since xy=30, we want to minimize

a = (x+2)(30/x + 4) = 4x+8 + 60/x

So, find x when da/dx = 0 to get the minimum area.