Linear equation in one variable class 8 NCERT solutions Part 3

Linear equation in two variable

The homogeneous system AX=0of n linear equation in n variables has (A) a unique solutions if |A|!=0 (B) infinitely many solution if |A|=0 (C) no solution (D) none of these

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

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.

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

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

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 x and that of a pen to be y).