Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 10 - Section 10.2 - Systems of Linear Equations in Several Variables - 10.2 Exercises - Page 697: 22

Answer

$x=1$ $y=-3$ $z=2$

Work Step by Step

Express y from the third equation. $x+y+z=0$ $-x+2y+5z=3$ $3x-y=6 \rightarrow y=3x-6$ Substitute $ y=3x-6$ into the first and the second equation. $x+3x-6+z=0$ $-x+2(3x-6)+5z=3$ Simplify. $4x+z=6$ $5x+5z=15$ Multiply the first equation by -5. $4x+z=6 \rightarrow -20x-5z=-30$ Add the equations to eliminate z. $-15x=-15$ $x=1$ Substitute for x and solve for y and z. $ 9x+z=6\rightarrow z=2$ $ y=3x-6\rightarrow y=-3$
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