Algebra 1: Common Core (15th Edition)

Published by Prentice Hall
ISBN 10: 0133281140
ISBN 13: 978-0-13328-114-9

Chapter 9 - Quadratic Functions and Equations - 9-5 Completing the Square - Practice and Problem-Solving Exercises - Page 579: 20


vertex: $( -9,-388)$

Work Step by Step

Consider the equation: $y=x^2+18x-307$ ...(1) The standard equation of the parabola is: $y=a(x-h)^2+k$ with vertex$(h,k)$ Consider right side $x^2+18x=307$ To complete the square add $(\frac{b}{2})^2=(\frac{18}{2})^2=81$. $x^2+18x+81=307+81$ $(x+9)^2=388$ Thus, equation becomes: $y=(x+9)^2-388$ Compare it with the standard form of the parabola, we get vertex: $( -9,-388)$
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