已知一8+2y=5,那么5(x一2y)的2次方一3(x一2y)一60的值为( )

问题描述:

已知一8+2y=5,那么5(x一2y)的2次方一3(x一2y)一60的值为( )

一x+2y=5
∴x-2y=-5
5(x一2y)²一3(x一2y)一60
=5×(-5)²-3×(-5)-60
=125+15-60
=80