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Question 116999This question is from textbook
: Solve by graphing.
2x = y + 1
2x - y = 5
I know you are supposed to rearrane it into y-intercept form but I'm not really sure how to go about graphing it at all.
This question is from textbook
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! Solve by graphing.
Actually these two equations have the same slope, therefore they are parallel lines and can't be solved by graphing or any other way.
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However this is the procedure and you will see what I mean:
Take one equation at a time:
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Put in slope/intercept form
2x = y + 1
Subtract 1 from both sides
2x - 1 = y
We can also write in the more familiar form:
y = 2x - 1
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Make a table to plot this as a graph, you only need 2 points, however here are 3
Let x = -3
Substitute -3 for x in the above equation and find y
y = 2x - 1
y = 2(-3)- 1
y = -6 - 1
y = -7
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The table:
x | y
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-3 |-7
do the same with x = 0
y = 2(0) - 1
y = -1
and
for x = +3
y = 2(3) - 1
y = +6 -1
y = + 5
the table now
x| y
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-3|-7
0|-1
+3|+5
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Plot these point on a standard +/- 10 graph, should look like this:
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Do exactly the same with this equation and plot on the same graph
2x - y = 5
-y = -2x + 5; subtracted 2x from both sides
y = +2x - 5; y always has to be positive, multiplied by -1
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You can see now that the two equations have the same slope (2)
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Plot this one using the values for x, -2, 0 +3
Substitute these values for x in the above equation,
x| y
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-2|-9
0|-5
+3|+1
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Anyway, if the graph of two equation intersect at some point, the x/y value of that point is the solution.
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