【3a2b-2ab+ab2】-【2a2b-2ab2+7ab】其中a=1,b=-2.化简求值.
问题描述:
【3a2b-2ab+ab2】-【2a2b-2ab2+7ab】其中a=1,b=-2.化简求值.
答
(3a²b-2ab+ab²)-(2a²b-2ab²+7ab)=3a²b-2ab+ab²-2a²b+2ab²-7ab)=a²b-9ab+3ab²当a=1,b=-2=1²×(-2)-9×1×(-2)+3×1×(-2)²=-2-(-...