1st, let's find the equation of the line connecting A(1 , 4) to B(0 , 3)
y = mx + b. Calculate the slope m = (y₂-y₁)/(x₂-x₁)
m = (3-4)/(0-1) and m = 1 → y = x + b. Now calculate b by replacing y and x by any coordinates of A either B
3 = 0.x + b → b = 3 and the final equation is y = x+3
If C(2,6) belongs to y = x + 3 that means if we plug in the values of x and y , we should have an equality:
y = x + 3
6 = 2 + 3 → so C doesn't belong to y = x+3
