Let the given points be A( 1, 3) and B(2, 7).
Let the line 3x + y - 9 = 0 divides the line segment AB in the ratio K : 1 at point P. Then the co-ordinates of P are given by
Here, we have
x1 = 1, y1 = 3
x2 = 2, y2 = 7
and m1 = K m2 = 1
So, co-ordinates of P are
But P lies on 3x + y - 9 = 0. ...(i)
Substituting the values of x (abscissa) and y (ordinate) in (i), we get
So, the required ratio be (3 : 4).