There is only one solution to the equation. Â A quadratic equation has 2 solutions a positive and a negative, but since we are looking for length, the answer can only be postive. Â Area= side^2
       400= x^2
     sqrt(400)=x
     20 inches = x Â
The length of one side is 20 inches
check: 20*20 = 400, which is the area of the square painting.