已知4x^2-3y^2=12,3x^2+2y^2=21,求代数式14x^2-2y^2的值.

分类: 作业答案 • 2021-12-19 15:01:39

问题描述：

答

4x^2-3y^2=12,3x^2+2y^2=21
两式相加,
7x^2-y^2=12+21=33

14x^2-2y^2
=2(7x^2-y^2)
=2*33
=66