Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 6 - Algebra: Equations and Inequalities - Chapter Summary, Review, and Test - Review Exercises - Page 405: 43

Answer

The trinomial\[{{x}^{2}}+2x+3\] is prime.

Work Step by Step

Note that this trinomial has leading coefficient is 1, therefore to factor it follow the steps below: Step 1: Find first two terms whose product is\[{{x}^{2}}\]. \[{{x}^{2}}+2x+3=\left( x\text{ } \right)\left( x\text{ } \right)\] Step 2: Find the last two terms which when multiplied gives \[3\]: \[\text{Factors of }3:\text{ }-1,-3\text{ }1,3\] Step 3: Now try various combinations of these factors and look for the pair of factors whose sum is the coefficient of the middle term. That is, \[2\]in this case. \[\begin{align} & \text{Factors of }3:\text{ }-1,-3\text{ }1,3 \\ & \text{Sum of factors : }-4\text{ }4\text{ } \\ \end{align}\] Since, none of the possible factors yields the sum \[2\]. This implies that the given trinomial cannot be factored using the integers and therefore, the trinomial\[{{x}^{2}}+2x+3\] is prime.
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