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Re: If (x + 3)2 = 225, which of the following could be the value
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08 May 2020, 04:32
I'm wondering why this one has so few correct answers. A lot of the time on the GRE quant I start to think diagnosing why so many get something wrong is better than diagnosing how they got it right.
Guessing most just root each side, see their answer of 11 doesn't exist, and guess. Key here is that when you take the root of a variable you have to set whatever was rooted to an absolute value. The absolute value must be considered as both possibly being positive and possibly being negative. Solve for each.
Re: If (x + 3)2 = 225, which of the following could be the value
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14 Jan 2021, 18:15
Thanks for the good explanations all. If I could summarize in my own words:
Step 1: Take the square root of each side. (x+3)^2 = 225. This turns into x+3 = 15 because 15 is the square root of 225. Step 2: We have two answers here because a square could have a negative and positive root (15^2 = 225, -15^2 = 225). x+3 = 15 OR x+3 = -15 Step 3: The first answer could be x = 15-3 = 12. 12-1 = 11. That is not in the answer choices so we can eliminate that answer. Step 4: The second answer could be x = -15-3 = -18. -18-1 = -19. That is in the answer choices so the correct answer is E, 19.