（a-2)²+丨b+1丨=0所以：a-2=0b+1=0a=2b= -12（2ab+5a²b）-3(a²b-ab）=4ab+10a²b-3a²b+3ab=7a²b+7ab=7×2²×（-1）+7×2×（-1）= -28+（-14）= -42