College Algebra (10th Edition)

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

Chapter 8 - Section 8.6 - Systems of Nonlinear Equations - 8.6 Assess Your Understanding - Page 614: 7

Answer

$(2.586,5.414)$ and $(5.414,2.586) \quad $(graphing) $(4-\sqrt{2},4+\sqrt{2})$ and $(4+\sqrt{2},4-\sqrt{2}) \quad$ (algebraically)

Work Step by Step

$\left\{\begin{array}{l}{y=\sqrt{36-x^{2}}}\\{y=8-x}\end{array}\right.$ Graphed with desmos.com/calculator. Substitute y into the second equation, $\begin{aligned}\sqrt{36-x^{2}}&=8-x\\36-x^{2}&=64-16x+x^{2}\\2x^{2}-16x+28&=0\\x^{2}-8x+14&=0\end{aligned}$ ... use the quadratic formula $x=\displaystyle \frac{8\pm\sqrt{64-56}}{2}=\frac{8\pm 2\sqrt{2}}{2}=4\pm\sqrt{2}$ $\left[\begin{array}{ll} x=4-\sqrt{2} & x=4+\sqrt{2}\\ \text{... back - substitute} & \\ & \\ y=8-(4-\sqrt{2}) & y=8-(4+\sqrt{2})\\ y=4+\sqrt{2} & y=4-\sqrt{2}\\ & \\ (4-\sqrt{2},4+\sqrt{2}) & (4+\sqrt{2},4-\sqrt{2})\\ & \end{array}\right]$ $(2.586,5.414)$ and $(5.414,2.586) \quad $(graphing) $(4-\sqrt{2},4+\sqrt{2})$ and $(4+\sqrt{2},4-\sqrt{2}) \quad$ algebraically)
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