1式:x+y=7
2式:xy=10
将1式变形x=7-y带入2式:
(7-y)*y=10
解得x=2,y=5或x=5,y=2;
1,x^2+y^2=2^2+5^2=29
2,(x-y)*(x-y)=9
(x-y)^4=81