Question

(x方+y方)(x方+y方-2)+1=0求x方+y方

Answer 1

(x方+y方)(x方+y方-2)+1=0
（x²+y²）²-2(x²+y²)+1=0
(x²+y²-1)²=0
x²+y²=1

Answer 2

x的四次方+y的四次方+2x²y²-2y²-2x²+1=0
﹙x²＋y²﹚²-2﹙x²＋y²﹚＋1=0
﹙x²＋y²-1﹚²=0
x²＋y²=1

Answer 3

设x^2+y^2=m，则方程变为m(m-2)+1=0，解得m1=m2=1，即x^2+y^2=1