Hello, could anyone help me with below question? This one comes from Kaplan, but I couldn't find an answer. Many thanks in advance!!

Which of the following expressions CANNOT be equal to 0 when x² − 2x = 3? A. x² − 6x + 9 B. x² − 4x + 3 C. x² − x − 2 D. x² − 7x + 6 E. x² − 9 x² - 2x - 3 = 0 (x-3)(x+1) = 0 x=3 or x=-1. Eliminate any answer choice that CAN be equal to 0 when x=3 or x=-1. A wise test-taker knows the following: When the question stem includes the phrase which of the following, the correct answer is likely to be D or E. E: x² − 9 If we plug x=3 into x² − 9, we get: 3² − 9 = 0. Eliminate E. D: x² − 7x + 6 If we plug x=3 into x² − 7x + 6, we get: 3² − 7*3 + 6 = -6. If we plug x=-1 into x² − 7x + 6, we get: (-1)² − 7(-1) + 6 = 14. x² − 7x + 6 cannot be equal to 0 when x=3 or x=-1. The correct answer is D.

Thanks Mitch, much appreciated for the detailed explanation! Could you explain what you mean by "When the question stem includes the phrase which of the following, the correct answer is likely to be D or E"? Is this something that likely pattern of return on the real GMAT test?

vinhaha wrote:Thanks Mitch, much appreciated for the detailed explanation! Could you explain what you mean by "When the question stem includes the phrase which of the following, the correct answer is likely to be D or E"? Is this something that likely pattern of return on the real GMAT test? Which of the following blah, blah, blah? The goal of the test-writer is to induce us to waste time. Here, the average test-taker will start with A. For this reason, the correct answer is likely to be D or E, inducing the average test-taker to waste time testing three or four incorrect answer choices. Thus: When the question stem includes the phrase which of the following, start with E and work your way up.

ASIDE: Whenever a question requires you to INSPECT each answer choice (as is the case with this question), the GMAT test-makers love to put the correct answer near the bottom. So, in these situations, I always suggest that students start at answer choice E and work their way up to A. Cheers, Brent

Brent@GMATPrepNow wrote:ASIDE: Whenever a question requires you to INSPECT each answer choice (as is the case with this question), the GMAT test-makers love to put the correct answer near the bottom. So, in these situations, I always suggest that students start at answer choice E and work their way up to A. Cheers, Brent Seconded! Incidentally, this also applies to Sentence Correction problems in which the whole sentence is underlined.