The line l has gradient 3 and cuts the x – axis at 4. Find its equation.

Answer 1

If line cuts the x - axis at 4 ,coordinates of this point are ( 4 , 0 )

The "point-slope" form of the equation of a straight line:

y - y1 = m ( x - x1 )

In this case:

x1 = 4 , y1 = 0

gradient m = 3

y - y1 = m ( x - x1 )

y - 0 = 3 ( x - 4 )

y = 3 x - 12