Stitz-Zeager_College_Algebra_e-book

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Unformatted text preview: ical to what we have developed here. 2.4 Inequalities 165 We remember that x denotes the number of TVs in hundreds, so if we are to ﬁnd our solution using the calculator, we need our answer to two decimal places. The zero5 2.414 . . . corresponds to 241.4 . . . TVs. Since we can’t make a fractional part of a TV, we round this up to 242 TVs.7 The other zero seems dead on at 5, which corresponds to 500 TVs. Hence to make a proﬁt, we should produce (and sell) between 242 and 499 TVs, inclusive. Our last example in the section demonstrates how inequalities can be used to describe regions in the plane, as we saw earlier in Section 1.2. Example 2.4.6. Sketch the following relations. 1. R = {(x, y ) : y > |x|}. 2. S = {(x, y ) : y ≤ 2 − x2 }. 3. T = {(x, y ) : |x| < y ≤ 2 − x2 }. Solution. 1. The relation R consists of all points (x, y ) whose y -coordinate is greater than |x|. If we graph y = |x|, then we want all of the points in the plane above the points on the graph. Dotting...
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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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