Hi, I need to find a width?

Question

The width of a rectangle is 6 meters less than twice it's length. If the area is 140 square meters, find the width?

I'm studying for finals...please help :(

Answer 1

this problem is written funny cause the "width" should be bigger than the "length" but here is how it goes.

We know that L*W=area so L*W=140.

Then we write the given info and substitute in:

W=2L-6  so we put that in for W in above equation

L(2L-6)=140

2L^2-6L-140=0 (distrubted and set equal to 0)

L^2-3L-70=-

(L-10) (L+7) =0

L=10 or L =-7 but a measurement can't be a negative so

L=10

W=2(10)-6 which equals 14

check W=14, L =10

so L*W=140 works