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# What is the value of r^2 - 2rs + s^2?

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Re: What is the value of r^2 - 2rs + s^2? [#permalink]
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inakihernandez wrote:
What is the value of $$r^2 - 2rs + s^2$$?

(1) $$s = 4$$
(2) $$r - s = 12$$

Target question: What is the value of $$r^2 - 2rs + s^2$$
This is a good candidate for rephrasing the target question.
Notice that $$r^2 - 2rs + s^2$$ is one of the special quadratic expressions
It can be factored as follows: $$r^2 - 2rs + s^2=(r-s)(r-s)=(r-s)^2$$
So....REPHRASED target question: What is the value of $$(r-s)^2$$?

Aside: the video below has tips on rephrasing the target question

Statement 1: s = 4
Since there's no information about r, there's no way to determine the value of $$(r-s)^2$$
Since we cannot answer the REPHRASED target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: $$r-s=12$$
PERFECT!!
This means that $$(r-s)^2=(12)^2=144$$
Since we can answer the REPHRASED target question with certainty, statement 2 is SUFFICIENT

Answer: B

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Re: What is the value of r^2 - 2rs + s^2? [#permalink]
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Re: What is the value of r^2 - 2rs + s^2? [#permalink]
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