What is the value of $$r^2−2rs+s^2?$$ (1) s=4
(2) r−s=12
The OA is the option B.
How can I use the statement (2) to get an answer? Experts, I'd like your explanation. Thanks in advanced.
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Target question: What is the value of r² − 2rs + s²?VJesus12 wrote:What is the value of $$r^2−2rs+s^2?$$
(1) s=4
(2) r−s=12
The OA is the option B.
This is a good candidate for rephrasing the target question.
Aside: Here's a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Notice that r² − 2rs + s² is a "special product"
It can be factored as follows: r² − 2rs + s² = (r - s)(r - s) = (r - s)²
REPHRASED target question: What is the value of (r - s)²?
Statement 1: s=4
No information about r, so statement 1 is NOT SUFFICIENT
Statement 2: r − s =12
This means (r - s)² = (12)² = 144
Since we can answer the REPHRASED target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
