2b+3b-3a-5b+3,其中a=-1.b=2,先化简,再求值

2b+3b-3a-5b+3,其中a=-1.b=2,先化简,再求值
2b+3b-3a-5b+3,其中a=-1.b=2,先化简,再求值

2b+3b-3a-5b+3,其中a=-1.b=2,先化简,再求值
=[2+3+(-5)]b+3a+3
=3a+3
当a=-1 b=2时原式：3a+3
=3*-1+3
=0

原式=（2+3-5）b-3a+3=-3a+3=3+3=6