The point-slope form is derived from the formula;
The equation of a line with point (x,y) and slope m is
THis is the point-slope form of a line.
From the previous example:
The equation of a line with slope -2 and the point (4,6)
y - 6 = -2( x - 4)
y - 6 = -2x + 8
2x + y = 14