College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 1 - Mid-Chapter Check Point - Page 165: 17

Answer

The equation has no $x$-intercept

Work Step by Step

$y=x^{2}-5x+8$ To find the $x$-intercepts of this equation, set $y$ equal to $0$ and solve for $x$: $x^{2}-5x+8=0$ Use the quadratic formula to solve this equation. The formula is $x=\dfrac{-b\pm\sqrt{b^{2}-4ac}}{2a}$ In this case, $a=1$, $b=-5$ and $c=8$ Substitute the known values into the formula and evaluate: $x=\dfrac{-(-5)\pm\sqrt{(-5)^{2}-4(1)(8)}}{2(1)}=\dfrac{5\pm\sqrt{25-32}}{2}=...$ $...=\dfrac{5\pm\sqrt{-7}}{2}=\dfrac{5}{2}\pm\dfrac{\sqrt{7}}{2}i$ Since the solutions of the equation are complex numbers, the original equation has no $x$-intercepts.
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