1: If each term in the sum a₁ + a₂ + a₃ + ... +a_n is either 7 or 77 and the sum is equal to 350, which of the following could equal to n?

38 39 40 41 42

How to handle this kind of questions? No clue.

2): If n & m are positve integers, what is the remainder when 3⁴ⁿ⁺² is divided by 10?

(1) n=2 (2) m =1

The answer is B. Why???

3: If the terms of a sequence are t₁, t₂, t₃, ... t_n, what is n:

(1) sum of n terms is 3,124 (2) average of the n term is 4

The correct answer is C

Thanks a lot

Which of the following lists the number of points at which  a circle can intersect a triangle?

问一个圆跟一个三角形的交点数的所有可能

1。设X个77，Y个7。

则77X+7Y=350

11X+Y=50

本题要求的是X+Y=?,设为M

联立上式有10X=50-M,隐含条件知X为整数，所以选项只有40满足条件

2。题目抄写有误吧

是不是what is the remainder when 3⁴ⁿ⁺² ＋m is divided by 10？

3的幂的尾数是有规律的。3⁴ⁿ⁺²（n为正整数）无论n为多少，其尾数都是9，m=1所以必然能被10整除，余数为0

3.总数＝n*平均数，n=总数/平均数，所以选C

第二题没有抄错数~~3⁴ⁿ⁺²，我也碰到这题了，根本都没有出现m啊

有trick? 哪位高人解答一下？？bow~

那我认为是BUG。

open to discuss

第二题，如果题目中没有Ｍ，则答案应该是Ａ

如果题目中有Ｍ，则答案应该是Ｃ