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先化简,在求值5(3a^b-ab^2-1)-(ab^2+3a^2b-5),其中a=-1/2,b=1/3
人气:281 ℃ 时间:2019-08-20 22:51:06
解答
题目应是 5(3a^2b-ab^2-1)-(ab^2+3a^2b-5)
=15a^2b-5ab^2-5-ab^2-3a^2b+5
=12a^2b-6ab^2
=6ab(2a-b)
=6*(-1/2)*(1/3)(2*(-1/2)-1/3)
=-3*(-1-1/3)
=4
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