Express the area of the table as a function of the length.

Question

A carpenter uses 20ft of oak to trim the eedges of a rectangular table. If the table is l feet long, express the are of the table as a function of the length. 

Answer 1

20 ft used to trim the edges of the rectangular  table  so the perimeter 2(l + w ) = 20

l + w = 10  the width,w = 10 - l 

the area of the rectangle = l* w =  l (10 - l ) = 10 l - l^2