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化简:当n=1/2时,求(3n-1)(n+1)+(2n-1)(n-1)的值.
人气:441 ℃ 时间:2020-03-28 17:39:50
解答
3n-1)(n+1)+(2n-1)(n-1)
=3n^2+3n-n-1+2n^2-2n-n+1
=5n^2-n
=5x(1/2)^2-1/2
=3/4
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