Question 715413
A^2+B^2=C^2
X^2+(X+4)^2=20^2
X^2+X^2+8X+16=400
2X^2+8X+16-400=0
2X^2+8X-384=0
2(X^2+4X-192)=0
(X+16)(X-12)=0
X-12=0
X=12 IN. ANS. FOR SIDE A.
12+4=16 IN. ANS. FOR SIDE B.
PROOF:
12^2+16^2=20^2
144+256=400
400=400