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