已知a+b=-4.ab=3.求2[ab+(-3a)]-3(2b-ab)的值

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已知a+b=-4.ab=3.求2[ab+(-3a)]-3(2b-ab)的值
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已知a+b=-4.ab=3.求2[ab+(-3a)]-3(2b-ab)的值
已知a+b=-4.ab=3.求2[ab+(-3a)]-3(2b-ab)的值

已知a+b=-4.ab=3.求2[ab+(-3a)]-3(2b-ab)的值
2[ab+(-3a)]-3(2b-ab)
=2[ab-3a]-6b+3ab
=2ab-6a-6b+3ab
=2ab+3ab-6a-6b
=5ab-6(a+b)
=5*3-6*(-4)
=15+24
=39

39

a+b=-4.ab=3.
a=-1 b=-3 或a=-3 b=-1
当a=-1 b=-3 2[ab+(-3a)]-3(2b-ab)=5ab-6a-6b=15+6+18=39
当 a=-3 b=-1 2[ab+(-3a)]-3(2b-ab)=5ab-6a-6b=15+18+6=39