[3a²-﹙ ﹚]÷﹙-a﹚=-3a=2b

问题描述:

[3a²-﹙ ﹚]÷﹙-a﹚=-3a=2b
是[3a²-﹙ ﹚]÷﹙-a﹚=-3a+2b

[3a²-﹙2ab﹚]÷﹙-a﹚=-3a+2b