Question

若a、b满足(a-3的二次方)绝对值b+三分之一等于0

则求代数式3a的二次方b—【2ab的二次方-2（ab-二分之三a的二次方b）+ab】+3ab的二次方，的值

Answer 1

若a、b满足(a-3的二次方)绝对值b+三分之一等于0

a-3=0 b+1/3=0
a=3 b=-1/3
代数式3a的二次方b—【2ab的二次方-2（ab-二分之三a的二次方b）+ab】+3ab的二次方的值

=3a^2b—【2ab^2-2ab+3a^2b+ab】+3ab^2
=3a^2b—【2ab^2-ab+3a^2b】+3ab^2
=3a^2b—2ab^2+ab-3a^2b+3ab^2
=ab^2+ab

=3*(-1/3)^2+3*(-1/3)
=1/3-1
=-2/3

Answer 2

若a、b满足(a-3的二次方)绝对值b+三分之一等于0
a-3=0 a=3
b+1/3=0 b=-1/3
代数式3a的二次方b—【2ab的二次方-2（ab-二分之三a的二次方b）+ab】+3ab的二次方，
=3a^2b-【2ab^2-2ab+3a^2b-2ab】+3ab
=3a^2b-2ab^2+2ab-3a^2b+2ab+3ab
=-2ab^2+7ab a=3 b=-1/3
=-2*3*(-1/3)^2+7*3*(-1/3)
=-2/3-7
=-23/3