Compare Quantity A and Quantity B, using additional information centered above the two quantities if such information is given,

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问题 Compare Quantity A and Quantity B, using additional information centered above the two quantities if such information is given, and select one of the following four answer choices:
(A)Quantity A is greater.
(B)Quantity B is greater.
(C)The two quantities are equal.
(D)The relationship cannot be determined from the information given.
A symbol that appears more than once in a question has the same meaning throughout the question.
r and t are consecutive integers and p = r2+t.
Quantity A         Quantity B
(-1)p     -1

选项

答案C

解析 Recall that

Since p = r2+ t, the value of(-1)p depends on whether r2 + t is odd or even.
If r is an odd integer, then r2 is an odd integer and, since r and t are consecutive integers, t is an even integer. In this case, p is the sum of an odd integer and an even integer and is therefore an odd integer.
Similarly, if r is an even integer, then r2 is an even integer and t is an odd integer. In this case, p is the sum of an even integer and an odd integer and is therefore an odd integer.
In both cases, p is an odd integer. It follows that(—1)p= -1, and the correct answer is Choice C.
This explanation uses the following strategies.
Strategy 1: Translate from Words to an Arithmetic or Algebraic Representation
Strategy 11: Divide into Cases
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本试题收录于: GRE QUANTITATIVE题库GRE分类
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