若A,B互為倒數,c,d互為相反數,求2c+2d-3ab

若A,B互為倒數,c,d互為相反數,求2c+2d-3ab

A,B互為倒數,則A*B=1
C,D互為相反數,則C+D=0
2c+2d-3ab
=2(c+d)-3a*b
=2*0-3*1
=0-3
=-3