# Introduction

**Click on instructions button for directions on how to use the component and solve the given problems.**

In the earlier classes, you have come across several **algebraic expressions** and **equations**. Some examples of expressions we have so far worked with are:

Some examples of equations are:

**You would remember that equations use the equality (=) sign; it is missing in expressions**.

Of these given expressions, **many have more than one variable**. For example, 2xy + 5 has

We however, restrict to **expressions with only one variable when we form equations**. Moreover, **the expressions we use to form equations are linear**. This means that the highest power of the variable appearing in the expression is

These are linear expressions:

**2x, 2x + 1, 3y – 7, 12 – 5z, **

These are **not** linear expressions:

Here we will deal with equations with linear expressions in one variable only. Such equations are known as **linear equations in one variable.** The simple equations which you studied in the earlier classes were all of this type.

Let us briefly revise what we know:

**(a)** **An algebraic equation is an equality involving variables**. It has an equality sign. The expression on the left of the equality sign is the **Left Hand Side (LHS)**. The expression on the right of the equality sign is the **Right Hand Side (RHS).**

**(b)** **In an equation the values of the expressions on the LHS and RHS are . This happens to be true only for certain values of the variable**. These values are the

**of the equation.**

**But what does it mean ?**

**For x = 5**: LHS = 2 × 5 – 3 =

**For x = 10**: LHS = 2 × 10 – 3 =

**Thus, x = 5 is a solution while x = 10 is not a solution of the equation**.

**(c)** **How to find the solution of an equation?** **We assume that the two sides of the equation are balanced.** We perform the same mathematical operations on both sides of the equation, so that the balance is not disturbed. A few such steps give the solution.