An equation which can be put in the form 
is called a linear equation in two variables 
and 
where a, b and c are real numbers and a and b are not both zero.
Here a and b are called coefficients of x and y respectively and c is called constant term.
The equation is called linear because the equation is of the first degree.
A solution is an ordered pair of real numbers which satisfies the equation.
In general, any linear equation in two variables will have infinitely many solutions.
An 
in the form of 
where a, b and c are real numbers and a and b are not both zero is called a linear equation in two variables x and y.
A linear equation in two variables has infinitely many solutions.
The solutions of a linear equation can be obtained by substituting different values for x in the equation to find the corresponding values of y.
The values of x and y are represented as an order pair.
To plot the graph of this equation, we’ll first find its solutions algebraically and then plot the points on the graph.
Any linear equation of the form 
represents a straight line on the graph.
Every point that satisfies the linear equation lies on the line.
Every point that lies on the line is a solution of the linear equation.
A point that does not lie on the line is not solution of the linear equation.
The equation of X axis is 
Any line parallel to x-axis is of the form y=k
The equation of y-axis is 
Any line parallel to y-axis is of the form x=k
ax+by+c=0
y=0
x=0
y=k
x=k
Note Blast 