(3a^2-ab+7)-(-4a^2+2ab+7)=

问题描述:

(3a^2-ab+7)-(-4a^2+2ab+7)=

(3a^2-ab+7)-(-4a^2+2ab+7)
=3a^2+4a^2-ab-2ab+7-7
=7a^2-3ab你确定对确定