己知:a2+2a+b2-4b+5=0,求ab的值?
问题描述:
己知:a2+2a+b2-4b+5=0,求ab的值?
答
a^2+2a+b^2-4b+5=0
a^2+2a+1+b^2-4b+4=0
(a+1)^2+(b-2)^2=0
a=-1,b=2
ab=-1*2=-2