Show that the distance between the points (x,y) and the line Ax + By + C = 0 is:

D = (Ax + By + C) / sqrt(A^2 + B^2)

So, would you start out by multiplying sqrt (A^2 + B^2) to both sides and then it would become:
sqrt (A^2 + B^2)D = Ax + By + C

Then square both sides,
D^2(A^2 + B^2) = (Ax + By + C)^2

Then I got lost, could someone direct me through this problem? Did I start out the right way? Thanks!

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- - x > 0
x