MBA考试

【单选题】S_n为a_n前n项和，a₁=3，S_n+S_n+1=3a_n+1，则S_n=( )
A．3ⁿ
B．3ⁿ⁺¹
C．3×2^n-1
D．3×2ⁿ⁺¹
E、2ⁿ⁺¹
网考网参考答案：C
网考网解析：
[解析] 因为S n +S n+1 =3a n+1 所以S n +S n +a n+1 =3a n+1 S n =a n+1 ，S n+1 =2S n S 1 =a 1 =3 S 2 =2S 1 =2a 1 =3×2 S 3 =2S 2 =3×2×2 [*] 所以S n =3×2 n-1 查看试题解析出处>>