Thinking Mathematically (6th Edition)

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

Chapter 6 - Algebra: Equations and Inequalities - Chapter 6 Test - Page 406: 21

Answer

\[2{{x}^{2}}-9x+10=\left( x-2 \right)\left( 2x-5 \right)\]

Work Step by Step

Let the factor of the provided expression is \[\left( ax+b \right)\left( cx+d \right)\]. Then, \[\begin{align} & 2{{x}^{2}}-9x+10=\left( ax+b \right)\left( cx+d \right) \\ & 2{{x}^{2}}-9x+10=ac{{x}^{2}}+\left( ad+bc \right)x+bd \end{align}\] Compare the coefficient, \[\begin{align} & ac=2 \\ & ad+bc=-9 \\ & bd=10 \end{align}\] The positive factor of 2 is\[\left( 1,2 \right)\]. And the factors of 10 are \[\left( 1,10 \right)\], \[\left( -1,-10 \right)\], \[\left( 2,5 \right)\], and \[\left( -2,-5 \right)\]. Then, the possible factorization of the expression \[2{{x}^{2}}-9x+10\]can be: \[\begin{align} & \left( x+1 \right)\left( 2x+10 \right)=2{{x}^{2}}+12x+10 \\ & \left( x-1 \right)\left( 2x-10 \right)=2{{x}^{2}}+12x+10 \\ & \left( x+2 \right)\left( 2x+5 \right)=2{{x}^{2}}+9x+10 \\ & \left( x-2 \right)\left( 2x-5 \right)=2{{x}^{2}}-9x+10 \end{align}\] \[2{{x}^{2}}-9x+10\]factors as \[\left( x-2 \right)\left( 2x-5 \right)\]. Therefore, the resultant factorization is: \[2{{x}^{2}}-9x+10=\left( x-2 \right)\left( 2x-5 \right)\]
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