求-2ab2+3a2b-2 (a2b-ab2 )的值,其中a=-1/3,b=9

问题描述:

求-2ab2+3a2b-2 (a2b-ab2 )的值,其中a=-1/3,b=9

-2ab²+3a²b-2 (a²b-ab² )
=-2ab²+3a²b-2a²b+2ab²
=a²b
=1/9×9
=1