Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 4 Quadratic Functions and Factoring - 4.1 Graph Quadratic Functions in Standard Form - Guided Practice for Example 3 - Page 238: 4

Answer

See the graph

Work Step by Step

Given: $y=x^2-2x-1$ The coefficients are $a =1$, $b =-2$, and $c=-1$. Because $a > 0$, the parabola opens up. Find the vertex. $x=-\frac{b}{2a}=\frac{-(-2)}{2.1}=1$ Then find the y-coordinate of the vertex. $y=1^2-2.1-1=-2$ Draw the axis of symmetry $x =1$ The y-intercept is $-1$. Plot the point $(0, -1)$. Then reflect this point in the axis of symmetry to plot another point, $(2,-1)$. Evaluate the function for another value of $x$, such as $x =-1$. $y=(-1)^2-2(-1)-1=2$ Plot the point $(-1, 2)$ and its reflection $(3, 2)$ in the axis of symmetry. Draw a parabola through the plotted points.
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