IB MAI HL Number and Algebra Topic 1.2 Sequences & Series (id: 0e3642650)

本题目来源于试卷: IB MAI HL Number and Algebra Topic 1.2 Sequences & Series，类别为 IB数学

[填空题]
A geometric sequence rko.s9y) gr+ 2gk*fzh .tt+ goh/(3v8t sakg ,4vy:,hacjkf vgyq kd49as $u_1$=5, u$_2$=-1 and u$_3$=$\frac{1}{5}$.
Find the common ratio, r.
$r = \frac{-1}{x}$,那么$x$ =   .
Find the exact value of u$_7$.
$u_7 = \frac{1}{x}$,那么$x$ =   .
Find the exact value of $S_7$.
$S_7 = \frac{13021}{x}$,那么$x$ =   .

参考答案:
空格1: 5  空格2: 3125  空格3: 3125 


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