SAT数学备考经典模拟题训练29

>>SAT数学模拟题：SAT数学备考经典模拟题训练29

>>SAT考试辅导

· Question #7: If f(x) = |x| and g(x) = x2, how many solutions has f(x) = g(x)?

(a) 1

(b) 2

(c) 3

(d) 4

(e) The equations does not have real solutions.

· Question #8: If a, b and c are the sides of any triangle, which of the following inequalities is not true?

(a) a·b > 0

(b) a + b > c

(c) a + c/2 >b

(d) b + c > a

(e) (a + b)·(b + c) > a·c

解析：

o Answer: The first answer is true, since the product of 2 positive reals will be positive.

The second and the fourth answers are also true, since the sum of 2 sides of a triangle is always higher than the third side.

The fifth answer is also true because it is just a multiplication of the second and fourth inequalities.

Answer three should be the one that is not true, and we can verify this result with an example: an isosceles triangle with a = 3, b= 3, c= 10 will not satisfy the inequality.

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