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Question 3193: How would you write an equation for a line that has an x-intercept of -1 and a y-intercept of 4?
Answer by drglass(89)   (Show Source):
You can put this solution on YOUR website! First, remember the equation of a line,
y = mx + b
where m is the slope of the line and b is the y-intercept.
The question tells you two points on the line. The first point is the x-intercept, we will call it P1 = (-1, 0), the second point is the y-intercept, which we will call P2 = (0, 4). We can find the slope of the line by
m =  =  = 4
Since we already know the value of the y-intercept is 4, the equation of the line is:
y = 
You can check this by setting x = 0,
So we get the point (0,4) from this equation.
Next set y = 0,
 subtract 4 from both sides to isolate x
 divide by 4 on both sides to get x by itself
This is the x-intercept (-1, 0) for the line. Our equation gives us the two points used to define the problem, therefore, it must be the correct equation.
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