Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 7 - Algebra: Graphs, Functions, and Linear Systems - 7.3 Systems of Linear Equations in Two Variables - Exercise Set 7.3 - Page 444: 5

Answer

See below:

Work Step by Step

The provided system of equations is: \[\begin{align} & x+y=6 \\ & x-y=2 \end{align}\] To solve it by graph method, plot the two lines in rectangular coordinate system. Use the following steps: Step 1: First graph the line \[x+y=6\]. Find x-intercept, set \[y=0\]in above equation. \[\begin{align} & x+y=6 \\ & x+0=6 \\ & x=6 \end{align}\] Find y-intercept, set \[x=0\]in above equation. \[\begin{align} & x+y=6 \\ & 0+y=6 \\ & y=6 \end{align}\] Plot the ordered pairs \[\left( 6,0 \right)\text{ and }\left( 0,6 \right)\]. Step 2: Draw a line passes through \[\left( 6,0 \right)\]and \[\left( 0,6 \right)\]. Step 3: Now graph the line \[x-y=2\]. Find x-intercept, set \[y=0\] in above equation. \[\begin{align} & x-y=2 \\ & x-0=2 \\ & x=2 \end{align}\] Find y-intercept, set \[x=0\]in above equation. \[\begin{align} & x-y=2 \\ & 0-y=2 \\ & y=-2 \end{align}\] Plot the ordered pairs \[\left( 2,0 \right)\text{ and }\left( 0,-2 \right)\]. Step 4: Draw a line passing through \[\left( 2,0 \right)\]and \[\left( 0,-2 \right)\]. Step 5: From the graph, point of intersection is \[\left( 4,2 \right)\]. To ensure that the graph is accurate, check the point of intersection\[\left( 4,2 \right)\]in both equations. \[\begin{align} & x+y=6 \\ & 4+2=6 \\ & 6=6 \end{align}\] \[\begin{align} & x-y=2 \\ & 4-2=2 \\ & 2=2 \end{align}\] Coordinates of the point of intersection \[\left( 4,2 \right)\] that satisfy both the equations. Hence, the graph of the system of equations is correct. Graph of the system of linear equations given above, these lines are intersecting at a point and coordinates of point of intersection is \[\left( 4,2 \right)\].
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