【单选题】下列关于数列的命题 ① 若数列 是等差数列,且 ( 为正整数)则 ② 若数列 是公比为2的等比数列 ③ 2和8的等比中项为±4 ④ 已知等差数列 的通项公式为 ,则 是关于 的一次 函数 其中真命题的个数为 ( )
【单选题】wind up对应
A.
To bring to an end by taking care of unfinished business
B.
n. the administration of an insolvent debtor’s property by the court for the benefit of the debtor’s creditors
C.
the joining together of two corporations in which one corporation transfers all of its assets to the other, which continues to exist. In effect one corporation "swallows" the other, but the shareholders of the swallowed company receive shares of the surviving corporation.
D.
n. a member of the governing board of a corporation or association elected or re-elected at annual meetings of the shareholders or members.
【单选题】下列说法中,正确说法的序号是 ( ) 1若数列{ }满足 = ,则这个数列是公比为2的等比数列; 2若等比数列{ }的公比 q=2, =-8,则其通项公式为 =- ; 3等比数列的公比不能为0; 4若数列{ }是各项均为正数的等比数列,则数列{ }不是等比数列.
【简答题】若 是等比数列, ,且公比 为整数,则 = .
【单选题】In the second paragraph, the word 'liquidate' probably means ______.
A.
wind up a company and pay back debts
D.
vote for a major decision
【简答题】.若果数列 的项构成的新数列 是公比为 的等比数 列,则相应的数列 是公比为 的等比数列,运用此性质,可以较为简洁的求出一类递推数列的通项公式,并简称此法为双等比数列法.已知数列 中, , ,且 . (1)试利用双等比数列法求数列 的通项公式; (2)求数列 的前 项和