Question

若绝对值x-1,+y的平方+4y+4＝0,求xy的值

Answer 1

|x-1|+y^2+4y+4

=|x-1|+(y+2)^2=0

因为|x-1|>=0,(y+2)^2>=0

则：

x-1=0

y+2=0

x=1

y=-2

xy=-2