Prep-1-168 80 145 192求助

請各位帮我解题〉《

谢谢了

192.  20681-!-item-!-187;#058&013102

On a certain day, Tim invested $1,000 at 10 percent annual interest, compounded annually, and Lana invested $2,000 at 5 percent annual interest, compounded annually.  The total amount of interest earned by Tim's investment in the first 2 years was how much greater than the total amount of interest earned by Lana's investment in the first 2 years?

(A)  $5

(B)  $15

(C)  $50

(D) $100

(E) $105

Ans: A

查到了作法, 但怎么看都不懂为蛇么要减去1000*(1+10%)? and 2000*(1+5%)??

[1000×（1＋10％）^2-1000*(1+10%)]-[2000*(1+5%)^2-2000*(1+5%)]=110-105=5

145.  14689-!-item-!-187;#058&010088

On her way home from work, Janet drives through several tollbooths.  Is there a pair of these tollbooths that are less than 10 miles apart?

(1)  The first tollbooth and the last tollbooth are 25 miles apart.

(2)  Janet drives through 4 tollbooths on her way home from work.

這裡是說每个toolbooth都一样距离吗？不懂. ANS:C

[?]

(A) If r and s are integers and rs + r is odd, which of the following must be even?

(B) r

(C) s

(D) r + s

(E) r^2 + s

Ans: B

想不出來WHY~~!!

168.  17696-!-item-!-187;#058&011204

For which of the following functions f is f (x) = f (1 - x) for all x ?

(A) f (x) = 1 - x

(B) f (x) = 1 - x^2

(C) f (x) = x^2 - (1 - x)^2

(D) f (x) = (x^2)(1 - x)^2

Ans: D