当a=-3时式子-3a【5a-3(a-4)-6]的值为

问题描述:

当a=-3时式子-3a【5a-3(a-4)-6]的值为

-3a[5a-3(a-4)-6]
=-3a[5a-3a+12-6]
=-3a[2a+6]
=-3*(-3)[2*(-3)+6]
=-3*(-3)[-6+6]
=-3*(-3)*0
=0