College Algebra (11th Edition)

Published by Pearson
ISBN 10: 0321671791
ISBN 13: 978-0-32167-179-0

Chapter 1 - Review Exercises: 53

Answer

$\text{Discriminant: } -124 \\\text{Number of distinct solutions: } 2 \\\text{Type of solutions: nonreal complex solutions }$

Work Step by Step

$\bf{\text{Solution Outline:}}$ To evaluate the discriminant of the given equation, $ -8x^2+10x=7 ,$ identify first the values of $a,b,$ and $c$ in the quadratic expression $ax^2+bx+c.$ Then use the Discriminant Formula. If the value of the discriminant is less than zero, then there are $\text{ 2 nonreal complex solutions .}$ If the value is $0,$ then there is $\text{ 1 rational solution .}$ If the value of the discriminant is a positive perfect square, then there are $\text{ 2 distinct rational solutions .}$ Finally, if the value of the discriminant is positive but not a perfect square, there are $\text{ 2 distinct irrational solutions .}$ $\bf{\text{Solution Details:}}$ In the form $ax^2+bx+c=0,$ the given equation is equivalent to \begin{array}{l}\require{cancel} -8x^2+10x-7=0 \\\\ -1(-8x^2+10x-7)=-1(0) \\\\ 8x^2-10x+7=0 .\end{array} In the equation above, $a= 8 ,$ $b= -10 ,$ and $c= 7 .$ Using the Discriminant Formula which is given by $b^2-4ac,$ the value of the discriminant is \begin{array}{l}\require{cancel} (-10)^2-4(8)(7) \\\\= 100-224 \\\\= -124 .\end{array} Since the discriminant is $\text{ is less than zero ,}$ then there are $\text{ 2 nonreal complex solutions .}$ Hence, the given equation has the following properties: \begin{array}{l}\require{cancel} \text{Discriminant: } -124 \\\text{Number of distinct solutions: } 2 \\\text{Type of solutions: nonreal complex solutions } .\end{array}
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