a₁+a₂+a₃=6,

a₂+a₃+a₄=-3,

S_n=a₁+a₂+…+a_n,

则S_n的值等于

A.               B.16                   C.24            D.32

A.-1                 B.                  C.0              D.∞

A.a=2,b=-4                                 B.a=-2,b=4

C.a=,b=-4                                D.a=-,b=

A.                  B.                C.              D.6

A.f(x)=1          B.f(x)=0        C.f(x)=0       D.f(x)=1

A.a_n=c                                           B.a_n=-c

C.a_n=c或a_n=-c                        D.以上都不对

A.不存在                 B.0                C.-7              D.7

A.［f(x)+g(x)］=a+b                 B.［f(x)+g(x)］=a+b

C.［f(x)+g(x)］=a+b                D.［5f(x)］+g(x)=5a+b