Linear equation in one variable

3x-2-7,3/2x+9=1/2, y/3+(y-2)/4=5 are linear equations in one variable, because the highest power of the variable in each equation in one whereas the equations 3x^2-2x+1=0, y^2-1=8 are not linear equations, because the highest power of the variable in each equation is not one. In this chapter, we shall study linear equations in one variable only.

Linear equation in two variable

If a pair of linear equations in two variables is consistent, then the lines represented by two equations are

Every point on the graph of a linear equation in two variables does not represent a solution of the linear equation.

The graph of every linear equation in two variables need not be a line.

Draw the graph of each of the following linear equations in two variables: -x+y=6 (ii) y=2x

If a pair of linear equations in two variables is consistent, then the lines represented by two equations are (a) intersecting (b) parallel (c) always coincident (d) intersecting or coincident

The cost of a notebook is twice the cost of a pen. Write a linear equation in two variables to represent this statement.(Take the cost of a notebook to be Rs x and that of a pen to be Rs y).