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Question 1151078: How do you graph 2x - y = -2
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website!
First solve for y
2x - y = -2
2x - y+y = -2+y ... add y to both sides
2x = -2+y
2x = y-2
y-2 = 2x
y-2+2 = 2x+2 ... add 2 to both sides
y = 2x+2
The last equation is in the form y = mx+b
m = slope = 2 = 2/1
b = y intercept = 2
The y intercept is 2, so we have the point (0,2) on the graph.
I'll mark this as point A.
This is where the graph crosses the vertical y axis number line.
The slope 2/1 tells us how to find another point on this line.
Start at point A, then move 2 units up and 1 unit to the right to arrive at point B which is located at (1,4)
Note that, slope = rise/run = 2/1. In other words, rise = 2 and run = 1. The rise tells us how much to go up or down. The run tells us how many units to go to the right. A negative rise means we go down as we read from left to right. In this case, the slope is positive so the positive rise means we go up as we read from left to right.
Here's what that looks like
A straight line is drawn through the two points to complete the graph. The green arrows and text are not part of the graph (they're just for educational purposes only). The points are optional to show your teacher.
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Alternatively, plug x = 1 into the equation y = 2x+2 and we get
y = 2x+2
y = 2(1)+2
y = 4
So x = 1 and y = 4 pair up to get (1,4). This helps confirm we have the proper location of point B.
Some more practice: plug in x = 2 to get...
y = 2x+2
y = 2(2)+2
y = 6
We have the point (2,6) on here as well. I'll label this point C.
I recommend you try various other x values to see what y values you get. It'll be good practice.
Here's the updated graph with point C added
Though you only need two points at minimum to form a straight line.
Graph images generated by GeoGebra (free graphing software).
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