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设A=2a²-a,B=-a²-a,求:A+B.A-B.2A-3B
人气:191 ℃ 时间:2020-04-03 18:50:56
解答
A+B
=2a²-a-a²-a
=a²-2a
A-B
=2a²-a+a²+a
=3a²
2A-3B
=4a²-2a+3a²+3a
=7a²+a
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