The x- intercept of the line joining the points  3,1 and 1,3  is

Equation of the line joining the points Px1,y1 and Qx2,y2 is  y−y1=y2−y1x2−x2x−x1Hence the equation of the line joining the points 3,1  and 1,3 is  y−1=3−11−3x−3To get x- intercept, substitute x=a,y=0 in the above equation  0−1=−1a−3a=3+1=4 Therefore, x-the intercept is 4