Intermediate Algebra: Connecting Concepts through Application

Published by Brooks Cole
ISBN 10: 0-53449-636-9
ISBN 13: 978-0-53449-636-4

Chapter 4 - Quadratic Functions - 4.4 Solving Quadratic Equations by the Square Root Property and Completing the Square - 4.4 Exercises - Page 349: 90

Answer

See graph

Work Step by Step

The function that we want to graph is shown below. Follow the steps outline to graph the function. $$ \begin{aligned} s(p) & =(p+7)^2-14. \end{aligned} $$ Step 1: We first determine the direction in which the function opens: The given function opens upward because the constant, $a= 1$ is positive. Step 2: Determine the vertex and the equation for the axis of symmetry. The vertex is $(-7,-14)$ and the equation for the axis of symmetry is $x = -7$. Step 3: Find the $y$ and $x$ intercepts. To find the $y$ intercept, set $x= 0$ to find the value of $y$. Similarly, to find the $x$ intercept, set $ y= 0$ to find the values of $x$. $$ \begin{aligned} s(0)& =(0+7)^2-14\\ &= 35\\ \textbf{y-intercept: (0,35)} \end{aligned} $$ Set $ y = 0$ and solve. $$ \begin{aligned} (p+7)^2-14 & =0\\ (p+7)^2&= 14 \\ p+7& = \pm\sqrt{14}\\ p&= -7\pm \sqrt{14}. \end{aligned} $$ Find the two separate solutions: $$ \begin{array}{cl} p= -7- \sqrt{14} &\text { or }\ p= -7+ \sqrt{14} \\ p= -10.74 & \text { or }\ p= -3.26\\ \textbf{x-intercepts: (-3.26,0), (-10.74,0)} \end{array} $$ Step 4: Find the domain and range of the function and sketch it. Domain: All real numbers, Range: $[-14, \infty) $.
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