RD Sharma Solutions for Class 8 Chapter 9 Includes Linear “Equation in One Variable”, A linear equation is an equation of a straight line, written in one variable. The only power of the variable is 1. Linear equations in one variable may take the form ax + b = 0 display style ax+b=0 ax+b=0 and are solved using basic algebraic operations. Here is an example of an identity equation. It includes Linear Equations by using few rules, which deal with solving equations having variable terms on one side and numbers on the other side. Transposition method for solving linear equations in one variable, cross-multiplication method for solving equations and lastly applications of linear equations to practical problems.