gaokao 2015 Q4

gaokao · China · national-II-science 5 marks Geometric Sequences and Series Finite Geometric Sum and Term Relationships
A geometric sequence $\left\{ a _ { n } \right\}$ satisfies $a _ { 1 } = 3 , a _ { 1 } + a _ { 3 } + a _ { 5 } = 21$ , then $a _ { 3 } + a _ { 5 } + a _ { 7 } =$
(A) $21$
(B) $42$
(C) $63$
(D) $84$
A geometric sequence $\left\{ a _ { n } \right\}$ satisfies $a _ { 1 } = 3 , a _ { 1 } + a _ { 3 } + a _ { 5 } = 21$ , then $a _ { 3 } + a _ { 5 } + a _ { 7 } =$

(A) $21$

(B) $42$

(C) $63$

(D) $84$