College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 4 - Section 4.3 - Quadratic Functions and Their Properties - 4.3 Assess Your Understanding - Page 299: 29

Answer

See image

Work Step by Step

Write $f$ in the form $f(x)=a(x-h)^{2}+k$: $\begin{aligned}f(x)&=-x^{2}-2x\\&=-\left(x^{2}+2x\right)\\&=-\left(x^{2}+2x+1\right)+1\\&=-(x+1)^{2}+1\end{aligned}$ Let $f_{1}(x)=x^{2}$. Then, $f(x)=-f_{1}(x+1)+1$. The graph is obtained from $f_{1}(x)$ by - reflecting about the x-axis $(x,y)\rightarrow(x,-y),$ - shifting to the left by 1 unit, - and then up by 1 unit Point by point, $\left[\begin{array}{lllll} (x,y) & \rightarrow & (x,-y) & \rightarrow & (x-1,-y+1)\\ & & & & \\ (0,0) & \rightarrow & (0,0) & \rightarrow & (-1,1)\\ (-1,1) & \rightarrow & (-1,-1) & \rightarrow & (-2,0)\\ (1,1) & \rightarrow & (1,-1) & \rightarrow & (0,0)\\ (-2,4) & \rightarrow & (-2,-4) & \rightarrow & (-3,-3)\\ (2,4) & \rightarrow & (2,-4) & \rightarrow & (1,-3) \end{array}\right]$
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