以下三题资料中给出的答案分别为 7.C 35.B 37.C
跟我算的不一样，是不是答案有问题？
Q7:
If x(x - 5)(x + 2) = 0, is x negative?
(1)x2 – 7x ≠ 0
(2)x2 –2x –15 ≠ 0
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Q35:
If n is a positive integer, which of the following is a possible value of |56 - 5n|?
A.7
B.9
C.12
D.15
E.20
Q37:
Working alone at their respective constant rates,machine A and machine B can fill a certain order in 3 hours and 6 hours, respectively.
If the two machines work simultaneously at their respective constant rates, how many hours does it take the two machines
to fill 1/2 of that order?
A.1/2
B.3/4
C.1
D.1 1/4
E.1 1/2
-- by 会员 lsuibear (2010/2/9 16:51:14)
(1) x*(x-7) not equal to 0, 所以 x 不等如0
(2) (x+3)(x-5) not equal to 0 , 所以 x-5 不等如0
綜合: x+2 等如0, x=-2
謝謝!! | 
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发表于 2010-2-9 16:51:14
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