Equation of a straight line  -  online calculator

 
Below you can use a calculator prepared to find the equation of a straight line. A line in a Euclidean space of dimension n is the set of the points whose coordinates satisfy a given set of n−1 independent linear equations.    
      

y = mx + b where: m is the slope of the line b is the y-intercept of the line x is the independent variable of the       function y = f(x)

The slope of the line through points (x₁, y₁) and (x₂, y₂) is given by
m = (y₂ – y₁)/(x₂ – x₁), and the equation of this line can be written 
y = m(x – x₁) + y₂ (notice that b = y₂).

This calculator has three sections: a) you enter two points, and the calculator returns slope (m) and intersect (b); b) you enter slope (m) and one point (x, y), and the calculator returns intersect (b); c) you enter slope (m) and one value (either x or y), and the calculator interpolates to deliver two points, both (value, y) and (x, value).

Example 1 - You know two points; calculate the slope and the y-intercept:

 
If you know two points that are on your line, the calculator returns m and b. For points (0, 1) and (0.25, 0), you fill in the blanks 

Point 1  = (0     1)
Point 2  = (0.25  0) 

and you get 

m = -4.0000      
b =  1.0000 

Example 2 - You know the slope and the y-intercept; calculate any two points on the line:

If you know the slope and the y-intercept, you can obtain the value of the function at any x or y-value. For a given m = -4 and b = 1, you can enter value = 1 (which means in this case both x = 1 and y = 1), like this:

m = -4     
b = 1
value = 1   

and you get points (x, y), first when x = value, and then when y = value.

(value, y) = (1.0000, -3.0000)    
(x, value) = (0.0000, 1.0000)