First, we need to calculate the slope
Firstly with the points A and B
(1,4)=(x1,y1)
(3,3)=(x2,y2)
then with A and C
(1,4)=(x1,y1)
(7,1)=(x2,y2)
then with C and B
(3,3)=(x1,y1)
(7,1)=(x2,y2)
because we obtain the same value of the slope we can say the points are collinear in other words the points are in the same line
the equation of the line is
the expression above is the equation using