Question

解方程:(x^2+4)^2-4(x^2+4)=5

Answer 1

2.题的答案是

x²+4xy+5y²+4x+2y+18

=x²+4xy+4y²+y²+2y+18

=(x+2y)²+(y+1)²+17>=17

当且仅当 x+2y=0 y+1=0 即 x=2 y=-1