先化简再求值6a(1-a)-(3a-7)(-3a-7),其中2a+a^2=-2

分类: 作业答案 • 2021-12-19 16:38:04

问题描述：

答

6a(1-a)-(3a-7)(-3a-7)
=6a-6a²-49+9a²
=3a²+6a-49
=3(a²+2a)-49
=-6-49
=-55

答

6a(1-a)-(3a-7)(-3a-7)
=6a-6a²+(3a)²-49
=3a²+6a-49
=3(a²+2a)-49
=3×(-2)-49
=-55