Finding the equation of a line.

First deduce the gradient through the formula Rise over Run. Then substitute the the co-ordinates of the first point to deduce the y-intercept.

To get a faster equation: Change the equation into the format (x/a + y/b = 1)

Ex. y = 1/2x - 3

1/2x + y = -3

x/-2 + y/1 = -3

x/6 + y/-3 = 1 //

However, if the the question asks for the equation in terms of y=mx+c, just do it like this:

x/6 + y/-3 = 1

-3x/6+y = -3

-1/2x + y = -3

y = 1/2x -3//

Question: When doing x/a + y/b = 1, why must it equal to 1?

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