Any line y = mx (where m is the slope) always passes through the point:
(0,0)
Let us take the line y = 2x.
If we take x = 0, we get y=2×0=0. This means that the line passes through (0,0) which is the origin. If we take any such equation of the form y = mx, and put x = 0, we will always get y = 0 because anything multiplied to 0 is equal to 0. Thus, any line of the form y = mx will pass through origin.