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-9a^2+[2a^2-2(a-3a^2)+5a](其中a=-2)
人气:181 ℃ 时间:2020-04-16 02:54:25
解答
-9a^2+[2a^2-2(a-3a^2)+5a]
=-9a^2+[2a^2-2a+6a^2+5a]
=-9a^2+[8a^2+3a]
=-9a^2+8a^2+3a
=-a^2+3a
=-(-2)^2+3*(-2)
=-4-6
=-10
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