Stitz-Zeager_College_Algebra_e-book

# 1 f x x x 2 g x x 2 x 3 1 solution 1

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Unformatted text preview: ﬁnition, we have √ |5| = (5)2 = 25 = 5 and | − 5| = (−5)2 = 25 = 5. The long and short of both of these procedures is that |x| takes negative real numbers and assigns them to their positive counterparts while it leaves positive numbers alone. This last description is the one we shall adopt, and is summarized in the following deﬁnition. Definition 2.4. The absolute value of a real number x, denoted |x|, is given by |x| = −x, if x < 0 x, if x ≥ 0 In Deﬁnition 2.4, we deﬁne |x| using a piecewise-deﬁned function. (See page 49 in Section 1.5.) To check that this deﬁnition agrees with what we previously understood as absolute value, note that since 5 ≥ 0, to ﬁnd |5| we use the rule |x| = x, so |5| = 5. Similarly, since −5 < 0, we use the rule |x| = −x, so that | − 5| = −(−5) = 5. This is one of the times when it’s best to interpret the expression ‘−x’ as ‘the opposite of x’ as opposed to ‘negative x.’ Before we embark on studying absolute value functions, we remind ourselves of the properties of absolute value. Theo...
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## This note was uploaded on 05/03/2013 for the course MATH Algebra taught by Professor Wong during the Fall '13 term at Chicago Academy High School.

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