Question 513474
The general the case can be illustrated with a simple example:
y = mx + b is the slope-intercept form of an equation
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m = slope
m = change in y / change in x
m = y-y<sub>1</sub> / x-x<sub>1</sub >
m = rise / run
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b = y-intercept, defined by the point (0,b)
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The x-intercept is (x,0).
So you set y=0 and solve for x
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y = 2x + 3
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m = 2, the coefficient of x
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when x=0, 
y = 2(0) + 3
y = 3
which is the point
(0,3)
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when y=0
0 = 2x + 3
2x = -3
x = -3/2
which is the point
(-3/2,0)
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With two points you can draw a line.
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{{{ graph(500,500,-5,5,-5,5,2*x+3) }}}
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Done.