求解释啊 ！！SAT 数学问题 哪位大侠 进来帮助下

zwj102030UID: 2938409

On a square gameboard that is divided into n rows of n squares each, k of these squares lie along the boundary of the gameboard. which of the following is a possible value for K?
5 Z4 {1 {1 L$ \A 10  B 25  C 34  D 42 E 52
6 l& _2 o# ?: [& W' ^2 ~1 f6 U这题什么意思 我看不懂 。。。。求解释
! M6 }9 x6 |4 I
还有题 OG TEST 4 Section 6 14 题
0 A2 t6 {' R, K8 q, L        a,3a...
* Q7 `7 M  i1 @% ]& h4 |' _the frist term in the sequence above is a, and each term after the first is 3 times the preceding term. IF the sum of the first 5 terms is 605 what is value of a

zwj102030UID: 2938409

我14题算出来答案是5  ， OG 答案是6。。。怎么算

zhaoxuan121UID: 2992222

意思是说一个square gameboard被分成了n*n块（n rows of n squares each：n行，每行 有n小块），然后说k of these squares lie along the boundary of the gameboard （k个小块是在这个gameboard的四周），问k等于多少。按照上面的说法，每周有n块，那么四周加起来总共就应该有4*(n-1)块，k=4*(n-1)，so k应该是4的倍数，这五个选项里只有E:52 可以被4整除，所以答案是E