Skip to Main Content

Source: Official Guide for GMAT Review 2016 Problem Solving; #17

4

If k^2 = m^2, which of the following

If k^2 = m^2, which of the following must be true?

1 Explanation

4

Jeffrey Braganza

Since the Q states K^2 = M^2
Means (5)^2 = (-5)^2 or (-5)^2 = (5)^2
K can be +ve or -ve
M can be +ve or -ve
[Every number has two square roots: positive and negative]

Now that we know what K & M should be: looking at answer choices (process of elimination)
A: K = +M
But K can be -ve too. Incorrect

B: K = -M
Again K can be +ve, Incorrect

C & D Incorrect for the same reason as A & B

E: |k| = |m|
Irrespective if K & M is +ve or -ve, taking the modulus will render only positive values. Hence E is the right answer
{Not sure if this is the right way to solve this}

Dec 31, 2015 • Comment

Cydney Seigerman, Magoosh Tutor

Yes, this is a valid approach to solve this problem :) Based on the original statement, k and m can be positive, negative, or 0. Since |k| = |m| regardless of the sign of either value within the absolute value, E satisfies the conditions of the statement.

Dec 31, 2015 • Reply

Add Your Explanation

You must have a Magoosh account in order to leave an explanation.

Learn More About Magoosh

Official GMAT Material

Official Guide for GMAT Review 2016

Official Guide for the GMAT 13th Ed.

Official Guide for the GMAT 2015 14th Ed.

Nova's GRE Prep

Official Guide for the GMAT 12th Ed.

Revised GRE PDF 2nd Ed.


Section 5.3 Problem Solving

Improve Your Score

Magoosh GMAT is an affordable online course for studying the GMAT.

Learn More About Magoosh

Share Post

Email

Facebook