The correct option is B 16 cm and 20 cm
The area of a square is side2 sq. units.
As per the question,
x2+(x+4)2=656
⇒x2+(x2+8x+16)=656
⇒2x2+8x−640=0
⇒x2+4x−320=0
⇒x2+20x−16x−320=0
⇒(x+20)(x−16)=0
Thus, x - 20 or 16.
But the side of a square can't be negative.
⇒x=16 and (x+4)=20.
Thus, the sides of the two squares are 16 cm and 20 cm.