已知ab=3,a+b=4.求3ab-[2a-(2ab-2b)+3]的值.

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

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

已知ab=3,a+b=4.求3ab-[2a-(2ab-2b)+3]的值.
3ab-[2a-(2ab-2b)+3]
=3ab-2a+(2ab-2b)-3
=3ab-2a+2ab-2b-3
=-2(a+b)+5ab-3
=-2 x 4 + 5 x 3 -3
=-8+15-3
=4

3ab-[2a-(2ab-2b)+3]
=3ab-2a+(2ab-2b)-3
=3ab-2a+2ab-2b-3
=5ab-2a-2b-3
=15-2(a+b)-3
=15-8-3
=4