NCERT Class 9 Mathematics Textbook for Blind Students made Screen Readable by Professor T K Bansal.

In this chapter, We have studied the following points:

1.
An equation of the form a x + b y + c = 0, where a, b and c are real numbers, such that a and b are not both zero, is called a linear equation in two variables.

2.
A linear equation in two variables has infinitely many solutions.

3.
The graph of every linear equation in two variables is a straight line.

4.
x = 0 is the equation of the y-axis and y = 0 is the equation of the x-axis.

5.
The graph of x = a, is a straight line parallel to the y-axis.

6.
The graph of y = a, is a straight line parallel to the x-axis.

7.
An equation of the type y = mx represents a line passing through the origin.

8.
Every point on the graph of a linear equation in two variables is a solution of the linear equation. Moreover, every solution of the linear equation in two variables is a point on the graph of the linear equation.

Acknowledgements
We at Blind to Visionaries Trust, are thankful to 1. Dr. T K Bansal, M.Tech, PhD (IIT Delhi), P.D.F (University of oxford) and former senior lecture from IIT Kharagpur, for planning, organizing and describing this lesson for visually impaired students
2. Mr. Arun kumar for typing and setting this lesson with full devotion and dedication, and for helping Dr T K Bansal in writing the alt text for each and every figure.
3. In case We suggest us any improvement or can point us any mistakes in this lesson your name will also be added to this list of contributors
4. Do We know the readers of this chapter are also the contributor’s! In case We take benefit of our efforts and encourage us by sending your comments, your name will also be added to this list.

End of the Chapter 4.