1 the sum of two numbers, x and y, equals twice their products. if x=3, what is the value of y?

　　这道题没大看懂?请问大家是这样么?x+y=2(x+y)

　　x+y=2xy,求y.

　　2 if x is an integer and x2(x的平方)<37,what is the greatest possible value of x minus the least possible value of x?

　　我觉得这道题x的最大值为6,最小值为0,所以选6.

　　a.5 b.6 c.10 d.12 e.36

　　选D，最大为6，最小为-6.

　　3 三角形ABC，角B=X度，X>90 度，比较三角形的周长与3倍AC的长度的大小，答案是B

　　AC是最大边,所以AB+BC+AC

　　2.0

　　比较the greatest value of p(1-p)与1/2的大小，答案是C

　　答案错了,选B p+(1-p)>=2p(1-p)^1/2 => p(1-p)<=1/4 < 1/2

　　4 for the line with equation y=ax+b,the x-intercept os twice the y-intercept

　　比较the slope of the line 与1/2的大小，答案是D，但算出来是-1/2呀

　　还有截距为零的情况,所以D.

　　5 a certain moneymarket account that had a balance of $48000 during all of last monthearned $360 in interest for the month. at what simple annual interestrate did the account earn interest last month?

　　答案是9%,题目没看懂

　　意思是一个货币市场上个月共结余48000，用它赚了360的利息，问以年单利计算每年利率是多少?

　　360*12/48000=9%