Question 325806
X^2+(X+21)^2=51^2
X^2+X^2+42X+441=2,601
2X^2+42X+441-2,601=0
2X^2+42X-2,160=0
2(X^2+21X-1,080)=0
2(X-24)(X+45)=0
X-24=0
X=24 ANS.
X+45=0
X=-45 ANS.