Let
x-------------> amount added <span>to each side
</span>A-------------> area increased----------> 84 ft²
we know that
A=(10+x)*(5+x)=84-----------> 10*5+10*x+5*x+x²
50+15x+x²=84----------> x²+15x-34=0
<span>solving the second order equation
</span>x1=-17
x2=2
the answer is x=2 ft
The maximum is 5, and the minimum is 1. The max. is in the are on the same side, which combines forces of 3 and 2. The min. uccors when they are on opposite sides.