College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter P, Prerequisites - Section P.2 - Real Numbers - P.2 Exercises - Page 17: 88

Answer

Since any rational number can be expressed as a fraction, and when 2 fractions are added, subtracted, or multiplied to each other, the result is always a fraction or a whole number, both of which are rational, the result will always be a rational number. The product of 2 irrational numbers can be rational, and the sum of 2 irrational numbers can also be rational.

Work Step by Step

The product of 2 irrational numbers is not always irrational because a non-perfect integer radical (for example, $\sqrt 2$) multiplied by itself will be rational. The sum of 2 irrational numbers is also not always irrational, because there could be a number like $3+\sqrt 5$that contains an integer and a radical. If this number is added to $ -\sqrt 5$, the result would be an integer, which is rational.
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