10.3 applications quadratic equations

Question

A rectangle has a length of 31 feet less than 6 times its width. If the area of the rectangle is 4470 square feet, find the length of the rectangle.

Answer 1

L= 6w -31

A=Lw = 4470

(6w-31)w = 4470

6w^2 -31w -4470

use the quadratic formula

w = 31/12 +/-(1/12)sqr(31^2 -4(6)(-4470))

simplify

then substitute that value for w to find L=6w-31,

check and see if that's also equal to L=4470/w