Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 10 - Review - Exercises - Page 772: 92

Answer

$(-2, 14)$ and $(4,-4)$

Work Step by Step

We can solve the system of equation using the graphical method and then confirm with algebraic operations. (a) Graphical method: read the coordinates of the intersection points of the line and the parabola, we get $(-2, 14)$ and $(4,-4)$ which are the solutions to the system. (b) Confirm with algebraic operations: Step 1. Use substitution method: from equation 1, we get $y=8-3x$ Step 2. Substitute it in the second equation to get $x^2-5x=8-3x$ or $x^2-2x-8=0$ Step 3. Factor the above equation to get $(x-4)(x+2)=0$ which gives $x=-2, 4$ Step 4. Back-substitute the results in the first equation to get $x=-2, y=14$ and $x=4, y=-4$ Step 5. The solutions to the system are $(-2, 14)$ and $(4,-4)$
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