If k^2 = h^2, which of the following must be true?  Choose the correct choice from the following answers:
A) k = m	B) |k| = |h|	C) k = |m|	D) k = -|m|	E) k = -m
Solution:   We are given that k^2 = h^2, and we can start by simplifying the equation by taking the square root of both sides.   √k^2 = √h^2   When we take the square root of a variable squared, the result is the absolute value of that variable. Thus:   √k^2 = √h^2 is |k| = |h|   Note that answer choices A through D could all be true, but each of them would be true only under specific circumstances. Answer choice E is the only one that is universally true.   Answer: k = -m
<result>E</result>
If k^2 = h^2, which of the following must be true?