What's the equation of the line containing the given pair of points.
(1,4) and (3,5)
Easiest way:
slope = 1/2
so the equation must be
x - 2y = c
but (1,4) lies on it, so
1 - 8 = c = -7
x - 2y = -7
or:
slope = 1/2
so the equation is
y = (1/2)x + b
but (1,4) lies on it, so
4 = (1/2)(1) + b
4 - 1/2 = b
b = 7/2
y = (1/2)x + 7/2 , which is the same as my first equation.