# SAT数学OG答案解析

2015-05-27 11:36 三立在线

SAT的官方备考资料OG一共有10套题，在最后有答案，但是没有解析的部分，今天三立在线的小编为各位考生推荐SAT数学OG答案解析的内容，考生们可以进行参考。

SAT数学OG答案解析预览

☆5. In a class of 78 students 41 are taking French, 22 are taking German and 9 students are taking both French and German. How many students are not enrolled in either course?

A. 6

B. 15

C. 24

D. 33

E. 54

☆6. If f(x) = │(x2 – 50)│, what is the value of f(-5) ?

A. 75

B. 25

C. 0

D. -25

E. -75

☆7. ( √2 - √3 )2 =

A. 5 - 2√6

B. 5 - √6

C. 1 - 2√6

D. 1 - √2

E. 1

Explanation:

You could solve this by drawing a Venn diagram. A simpler way is to realize that you can subtract the number of students taking both languages from the numbers taking French to find the number taking only French. Likewise find those taking only German. Then we have:Total = only French + only German + both + neither

78 = (41-9) + (22-9) + 9 + neither.

Not enrolled students = 24

Explanation:

If x = -5, then (x2 – 50) = 25 – 50 = -25

But the sign │x│ means the absolute value of x (the distance between the number and zero on the number line). Absolute values are always positive.

│-25 │ = 25

Explanation:

Expand as for (a + b)2.

(√2 - √3)(√2 - √3) = 2 - 2(√2 + √3) + 3 = 5 - 2 √6

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