Question

数列An=n-根号79/n-根号80,在前50项中求最大项和最小项.

Answer 1

An=(n-√80+√80-√79)/(n-√80)

1+(√80-√79)/(n-√80)

因为:√80-√79>0,所以此函数y=1+(√80-√79)/(x-√80)在(-无穷,√80)减且负,(√80,+无穷)减且正.

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