(1)方程变形得:x2-4x=-1,
配方得:x2-4x+4=3,即(x-2)2=3,
开方得:x-2=±
3,
解得:x1=2+
3,x2=2-
3;
(2)原式=
x2−y2+y2
(x+y)(x−y)•[x−y/x]=[x/x+y].