What is an Identity in Math – Example of Identity in Math

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Your “identity” indicates who you are, how you view yourself, how other people see you, and the qualities that define who you are.

We have an identity in mathematics, similar to your personal identity, and in today’s article, we will discuss what is an identity in math?

When all the variables used in equality are changed, the equality still remains true, this is known as an identity.

The concept of identity has many important uses in mathematics. In this article, you will learn identity math definition, an example of identity in math, corbettmaths solving equations and many more.

Keep reading!

Definition of Identity in Maths

In terms of mathematics, we are often confused as to what is an identity in math?
A mathematical identity is defined by Wikipedia as the equality of one expression A to another expression B when A and B give the same result for all possible values of the variables within a given range of validity.
For example, a/2 = a 0.5 holds true regardless of the value selected for “a.”

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Common Identities in Maths

Some of the most common identities in mathematics are listed below.

  • Algebraic

It refers to a small number of identities, such as displaystyles a+0=a and a+(-a)=0, while additional identities, like (a+b)2=a2+2ab+b2 and a2 – b2=(a+b)(a-b), can be helpful in simplifying algebraic formulas.
The algebraic identities chart highlights the identity’s development through remarkable geometric representation.

Identities in Maths
refers to a small number of identities
  • Trigonometric

These identities are identities that include certain functions of one or more angles.
They differ from triangle identities, which are identities that involve both a triangle’s angles and side lengths.
The equation sin2 θ + cos2 θ = 1 is one of the most well-known examples of a trigonometric identity, which applies to all actual values of θ.

  • Exponential

If the base is not zero, the following identities apply to all integer exponents:
It is not commutative, in opposed to addition and multiplication. For example, 2 + 3 = 3 + 2 = 5 and 2 • 3 = 3 • 2 = 6, but 23 = 8 and 32 = 9 respectively.

  • Logarithmic

Several essential equations are also known as logarithmic identities or log laws.
The sum of the logarithms of the numbers being multiplied creates the logarithm of the product. The difference between the logarithms creates the logarithm of the ratio of two numbers.

  • Hyperbolic

Many identities that are similar in form to the trigonometric identities are satisfied by the hyperbolic functions.
Any trigonometric identity can be changed into a hyperbolic identity by completely increasing it in terms of integer powers of sines and cosines, according to Osborn’s rule.
Changing sine to sinh and cosine to cosh, and changing the sign of every term that contains a product of an even number of hyperbolic sines.

Common Problems and Solutions

The following information will help you solve common mathematical problems.

  • Solving linear equations corbettmaths
    Identify each of the following as an equation or an identity:
  • 5x+10=3x+8
  • 5x+10=5(x+2)
  • 5x+10=5x+2


  • The equation to the left of the equals sign cannot be adjusted to create the equation to the right, proving that this is an equation. x=1 is the answer to the equation.
  • This is an identity because the expression is the same when the bracket to the right of the identity sign is extended as it is to the left.
  • Because the expression to the left of the equals sign cannot be changed to get the equation to the right, this is an equation.
    No matter what value of x is used in the equation, the expression on the left will never equal the expression on the right, showing that the equation has no solution.
  • Forming and solving equations corbettmaths

A rectangle is shown in the diagram. Centimetres are used to measure the sides.

  • Describe why 5x + 3 = 3x + 9
    Solution: A rectangle’s opposite sides are equal in length, so 5x+3 = 3x+9
Problems and Solutions
Identify each of the following as an equation or an identity


What is an example of identity in algebra?

The identity (x + y)2=x2+2xy+y2 for example, remains true for all values of x and y.

What is an identity in an algebra equation?

An identity equation is one that holds compared to the value entered for the variable.

How do you tell if an expression is an identity?

The quickest way to tell if an equation is identity is to graph the difference between its two sides.

How do you know if an equation is not an identity?

If the two expressions differ at any one input, the equation cannot be an identity.

Because an identity must ensure equality for each possible value of the variable.

What is a symbol of identity?

The identity symbol is (≡).

What is the identity of a B3?

(a – b)3 = a3 – 3a2b + 3ab2 – b3 = a3 – b3 – 3ab(a – b)

What Does It Take to Be a Mathematician?

Your time may vary depending on the academic route you choose; getting an advanced mathematics degree can take 6–8 years.

What is the meaning of identity property?

The sum of 0 and any number is that number, according to the identity property of addition. For instance, 0 + 4 equals 4 and 0 + 4 equals 40.

Is the equation an identity?

An identity is an equation, despite of the values used, which is always true.

What does the word “multiplicative identity” mean in math?

An element in a particular system leaves any element by which it is multiplied unchanged. An example of an identity element is 1 in the group of real numbers without a 0.


A person who has a positive sense of identity in mathematics finds the subject interesting.
Understanding identity in math is crucial because it helps us answer various questions more quickly. It makes the calculation easier.
I really hope this article has improved your understanding of what is an identity in math.

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