Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 9 - Systems and Matrices - 9.5 Nonlinear Systems of Equations - 9.5 Exercises - Page 904: 22

Answer

$$\left\{ {\left( {\frac{{38}}{{25}},\frac{{41}}{{25}}} \right),\left( { - 2, - 1} \right)} \right\}$$

Work Step by Step

$$\eqalign{ & \,\,\,\,\,\,{x^2} + {y^2} = 5\,\,\,\,\,\,\,\left( {\bf{1}} \right) \cr & \, - 3x + 4y = 2\,\,\,\,\,\,\left( {\bf{2}} \right) \cr & \cr & {\text{Solve the equation }}\left( {\bf{2}} \right){\text{ for }}y \cr & y = \frac{{3x + 2}}{4} \cr & {\text{Substitute }}\frac{{3x + 2}}{4}{\text{ for }}y{\text{ into the equation }}\left( {\bf{1}} \right) \cr & {x^2} + {\left( {\frac{{3x + 2}}{4}} \right)^2} = 5 \cr & {x^2} + \frac{{9{x^2} + 12x + 4}}{{16}} = 5 \cr & 16{x^2} + 9{x^2} + 12x + 4 = 80 \cr & 25{x^2} + 12x - 76 = 0 \cr & \left( {25x - 38} \right)\left( {x + 2} \right) = 0 \cr & {x_1} = \frac{{38}}{{25}},\,\,\,{x_2} = - 2 \cr & {\text{Substitute }}{x_1} = \frac{{38}}{{25}}{\text{ into the equation }}y = \frac{{3x + 2}}{4}{\text{ to find }}\left( {{x_1},{y_1}} \right) \cr & y = \frac{{3\left( {38/25} \right) + 2}}{4} \cr & y = \frac{{41}}{{25}} \cr & {\text{The first solution is }}\left( {\frac{{38}}{{25}},\frac{{41}}{{25}}} \right) \cr & \cr & {\text{Substitute }}{x_2} = - 2{\text{ into the equation }}y = \frac{{3x + 2}}{4}{\text{ to find }}\left( {{x_2},{y_2}} \right) \cr & y = \frac{{3\left( { - 2} \right) + 2}}{4} \cr & y = - 1 \cr & {\text{The second solution is }}\left( { - 2, - 1} \right) \cr & \cr & {\text{Therefore, the solution set of the system is}} \cr & \left\{ {\left( {\frac{{38}}{{25}},\frac{{41}}{{25}}} \right),\left( { - 2, - 1} \right)} \right\} \cr} $$
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