Question

若x的平方+Y+2X-4倍根号Y+5=0求根号下-XY的值

Answer 1

x^2+2x+1+y-4√y+4=0,

(x+1)^2+(√y-2)^2=0

当且仅当x=-1,√y=2时等式成立,

x=-1,y=4,

√（-xy）=√4=2.