2. the rate of a certain chemical reaction is directly proportional to the square of the concentration of clemical A present and inversely proportional to the concentraion of chemical B present. If the concentration of chemical B is inceased by 100%, which of the following is closet to the percent change in the centration of chemical A required to keep the reaction rate unchanged? 答案是40% 这道题目就没怎么看懂，有哪位看明白的帮忙翻译一下？ 再解释解释做法？ 那个B inversely react又说明什么了？这两个reaction是怎么反应的？ 该用乘法还是加法呀？
3。what is the greatest common devisor of positive intefer m and n? (1)m is a prime number (2) 2n=7m 求具体解释~
4。If x and y are integers greater than1, is x multiple of y? (1）3(y^2)+7y=x (2) x^2-x is a multiple of y 答案是A，我选了D 因为（1）把y提出来除到右边，x/y=3y+7 结果是个整数，所以x是y的multiple (2) x(x-1)是y的倍数，x和x-1是相邻的两个数，x或x-1是y的倍数， 另一个就做一个乘数 所以两个都可以啊 选D啊
5。if the integer a and n are greater than1, and the product of the first 8positive integers is a multiple of a^n, what is value of a? (1)a^n=64, (2) n=6 答案是B， 单独一个（2）怎么算啊~
6。If the terms of a sequence are t1,t2...tn, what is the value of n？ （1）the sum of the n integers is 3124 (2) the average mean of the n terms is 4 求算法