prep一数学题 求解答

dididadaya

For every integer k from 1 to 10, inclusive, the kth term of a certain sequence is given by
.If T is the sum of the first 10 terms in the sequence, then T is


(A) greater than 2

(B) between 1 and 2

(C) between 1/2 and 1

(D) between 1/4 and 1/2

(E) between 1/4

dididadaya

given by 后面是个公式 （-1）的k+2次幂，乘以      1
                                                                              ————
                                                                            2的k次幂

站在刀尖舞蹈

什么叫“the kth term of a certain sequence is given by" ? given by神马？囧