SAT数学备考经典模拟题训练18

>>SAT数学模拟题：SAT数学备考经典模拟题训练18

>>SAT考试辅导

5. If n > 0 , which of the following must be true?

I n² > 1

II n - n² < 0

III 2n - 1 > 0

A. I only

B. II only

C. III only

D. I and II only

E. none

6. If the slope of a line is ½ and the y-intercept is 3, what is the x-intercept of the same line?

A. 6

B. 3/2

C. 0

D. -2/3

E. -6

5.Correct Answer: E

Explanation:

Given that n is positive, it could be a positive fraction, 1, or a fraction of whole number greater than 1.

If n = 1, then case I is not true since n2 = 1

Likewise in II if n = 1, n - n2 = 0, and the statement is not true.

In III, if n = ½, then 2n - 1 = 0, and again the statement is incorrect.

6.Correct Answer: E

Explanation:

The equation for a straight line is y = mx + c, where m = slope and c = y-intercept.

Putting the given values in this equation we have y = x/2 + 3

The x-intercept occurs where y = 0. Thus, 0 = x/2 + 3 ; -3 = x/2 ; -6 =x

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