Mathematics is known as “Queen of Science”. We use concepts of mathematics everywhere, every day, almost in every situation. So far we have used lots of numbers, lots of shapes and figures. Here we are going to use some letters in math. It is a special branch of mathematics which deals with numbers, shapes and letters. Yes, it is algebra; let’s learn more about it.

## ALGEBRA: EXPRESSIONS & EQUATIONS

Mathematics has been classified into many branches. Arithmetic is the branch which handles numbers and their operations. Arithmetic taught us addition, subtraction, multiplication and divisions of two or more numbers. Geometry is all about shapes and their construction using different tools like a compass, ruler and pencil. Algebra is another interesting branch where we express our daily life situations in the form of numbers and letters (variables).

To understand algebra we need to know what an expression is and what an equation is.

### EXPRESSIONS

An expression or algebraic expression is any mathematical statements which consist of numbers, variables and an arithmetic operation between them. For example, *4m + 5* is an expression where 4*m* and 5 are the terms and *m* is the variable of the given expression separated by the arithmetic sign +.

Variable is anything that varies; it doesn’t have a fixed value. Generally, variables of an expression are represented by alphabetical letters like a, b, c, m, n, p, x, y, z, and so on. We can form a variety of expressions using a combination of different variables and numbers. *x+5y-10, 2x+1, x+y*, are few examples of expressions.

### EQUATIONS

The equation is an expression where two sides of the expression are connected through an equal to sign (=). *2x+1=9* is an equation, where *2x+1* is the left-hand side (LHS) and 9 is the right-hand side (RHS) of the expression. The equal sign between LHS and RHS indicates that the value of LHS is equal to the RHS of the expression.

*10x+63>10*, is not an equation. Here, the sign between LHS and RHS of the expression is not an equal sign. Hence, we can say every expression is not an equation.

Some other examples of algebraic equations are, *8m+5=10n, a+4b=12c+3* .

NOTE: *An equation is interchangeable i.e. the equation remains same even if LHS and RHS interchange each other. *

* *Equations *8m+5=10n *and* 10n= 8m+5* are same.

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