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
