问题
选择题
若a,b为有理数,且2a2-2ab+b2+4a+4=0,则a2b+ab2=( )
A.-8
B.-16
C.8
D.16
答案
解;∵2a2-2ab+b2+4a+4=0,即a2-2ab+b2+a2+4a+4=0,
∴(a-b)2+(a+2)2=0,
故a-b=0,a+2=0,
解得:a=-2,b=-2.
故a2b+ab2=ab(a+b)=-16.
故选B.
若a,b为有理数,且2a2-2ab+b2+4a+4=0,则a2b+ab2=( )
A.-8
B.-16
C.8
D.16
解;∵2a2-2ab+b2+4a+4=0,即a2-2ab+b2+a2+4a+4=0,
∴(a-b)2+(a+2)2=0,
故a-b=0,a+2=0,
解得:a=-2,b=-2.
故a2b+ab2=ab(a+b)=-16.
故选B.