[Mathematics] Linear equation: two-point equation

Although slope-intercept form is more common to find out the function of a linear equation, we can also use another method named "2 points equation" to get the function.
The advantage using this method is you don not need to know the slope.

Read more about slope-intercept form :
[Mathematics] Linear equation: slope-intercept form

equation of two-point equation:

where (x₁ , y₁) and (x₂ , y₂) are points on the line.

Let use this graph as example, we pick out 2 points (0,1) and (1,3) on the line:

put x₁ = 0, y₁ =1, x₂ =1, y₂=3 into the equation:

And here we got the function y=2x+1