两道SAT数学题及解题方法

2022-05-25 07:25:59

  下面为大家介绍的是两道

  1、The stopping distance of a car is the number of feet that the car travels after the driver starts applying the brakes. The stopping distance of a certain car is directly proportional to the square of the speed of the car, in miles per hour, at the time the brakes are first applied. If the car’s stopping distance for an initial speed of miles per hour is feet, what is its stopping distance for an initial speed of miles per hour?

  Answer Choices

  (A) feet

  (B) feet

  (C) feet

  (D) feet

  (E) feet

  2、If is divisible by , , and , which of the following is also divisible by these numbers?

  Answer Choices

  (A)

  (B)

  (C)

  (D)

  (E)

  Explanation:

  1、The correct answer is D

  The stopping distance is directly proportional to the square of the initial speed of the car. If represents the initial speed of the car, in miles per hour, and represents the stopping distance, you have that the stopping distance is a function of and that , where is a constant. Since the car’s stopping distance is feet for an initial speed of miles per hour, you know that . Therefore, , and the car's stopping distance for an initial speed of miles per hour is feet.

  2、The correct answer is D

  Since is divisible by , , and , must be a multiple of , as is the least common multiple of , , and . Some multiples of are , , , , and .

  If you add two multiples of , the sum will also be a multiple of . For example, and are multiples of and their sum, , is also a multiple of .

  If you add a multiple of to a number that is not a multiple of , the sum will not be a multiple of . For example, is a multiple of and is not. Their sum, , is not a multiple of .

  The question asks which answer choice is divisible by , , and ; that is, which answer choice is a multiple of . All the answer choices are in the form of "plus a number." Only choice (D), , has added to a multiple of . The sum of and is also a multiple of , so the correct answer is choice (D).

  以上就是这两道SAT数学题的全部内容,后面的题目解答方法非常详细。大家可以在备考SAT数学考试的时候,利用题目对自己 掌握的知识点进行适当的检查和测试,以找出不足之处进行更改。

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