急問幾道GRE數學題!
都是綠皮上的,本人數學不大好,
185.20
For which of the following pairs of integers is the least common multiple of the integers minus their greatest common divisor the greatest?
　　A.3,12 B.5,6 C.10,20 D.11,12 E.15,30
275.34
If 1 is the greatest common divisor of the
positive integers a and b and if a/b-1=13/8.Then a+b=?
A.11 B 13 C20 D21 E29
158.30
Which of the following cannot be expressed
as the sum of either two or three consecutive positive integer?
A.17 B18 C42 D56 E65
266.17
If n is an integer,then the units digit of
n^2 cannot be?
A0 B2 C4 D5 E6