(a-1/2)的二次方+ |a+b+3 | =0∴a-1/2=0a+b+3=0∴a=1/2 b=-7/2 （-a的三次方+3ab-1/2b的二次方）-（-2a的二次方+4ab-1/2b的二次方）=-a³+3ab-b²/2+2a²-4ab+b²/2=-a³-ab+2a²=-1/8+7/4+1/2=17/8
17\8，没错
