Question

you are building a rectangular wading pool you want the area of the bottom to be 90 ft squared you want the length of the pool to be 3 ft longer than twice its width what will the dimensions of the pool be

Answer 1

L=2W+3, A=LW, using L from the first in the second gives you:

A=(2W+3)W

A=2W^2+3W, and we are told A=90 so

2W^2+3W=90

2W^2+3W-90=0

2W^2-12W+15W-90=0

2W(W-6)+15(W-6)=0

(2W+15)(W-6)=0, since W>0 for all real possibilities, 

W=6ft, and since L=2W+3

L=15ft

So the pool will be 6 ft wide by 15 ft long.