Answer: ≈40.2
Explanation:
(2x-1)*(x+1)=90
Distribute
2x^2-1=90
Add 1 to both sides.
2x^2=91
Divide both sides by 2
x^2=45.5
Square both sides.
x≈6.7
Check work by plugging x into both original sides and multiplying them.
(2(6.7)-1)*((6.7)+1)=90
12.4*7.7=95.48
Side lengths are approximately 12.4 and 7.7.
12.4*2=24.8
7.7*2=15.4
24.8+15.4=40.2