题目应该是(1^2+99^2)/(49^2+50^2)
简便算法
=(50-49)^2+(50+49)^2/49^2+50^2
=50^2-2*50*49+49^2+50^2+2*50*49+49^2/49^2+50^2
=49^2+50^2+49^2+50^2/49^2+50^2
=2