已知aa+bb=3,则多项式4aa-3ab-2bb+aa+3ab+7bb的值为多少?

问题描述:

已知aa+bb=3,则多项式4aa-3ab-2bb+aa+3ab+7bb的值为多少?

4aa-3ab-2bb+aa+3ab+7bb
=(4+1)aa+(-3+3)ab+(-2+7)bb
=5aa+5bb
=5(aa+bb)
=5×3
=15