What are Expressions?

An Expression is a number, a variable, or a combination of numbers, variables, and operation symbols.

For example,

• x + 3
• y - 10
• 19 x ³

An expression can be of one of the following two types:

(i)Numerical expression

This is an expression that consists only of numbers. For example,

• 13 + 6
• 15 - 5
• 16 x 15

(ii)Algebraic expression

This is an expression that consists of only variables or variables and numbers together. For example,

• 6 + y
• x - 12
• 15xy
• z

What are Equations?

An Equation is two expressions connected by an equal sign (=). For example,

• y - 10 = 6 + x
• 13 = 15x
• xy = 17x + 2

What are the different parts of an equation?

An equation consists of:

• Variables: The letters used to represent unknown quantities are called variables.
• Constants: The numbers in an equation whose value remains unchanged are called constants.
• Mathematical operators: The operators used in an equation to carry out mathematical operations such as addition, subtraction, square root etc. are known as mathematical operators.

The equal sign divides every equation into two parts: the left-hand side (L.H.S.) and the right- hand side (R.H.S.).