# The Laws of Exponents in Algebra(KS3, Year 7)

## The Lesson

The laws of exponents are rules for using exponents in algebra. Imagine you see a letter that has an exponent. For example, the letter a with an exponent of 2. In this example, a (called the base) is multiplied by itself 2 (the exponent) times. What if we see the a letter with an exponent multiplying that same letter with a different exponent? Or dividing? What if the exponent is negative? Or a fraction? We need to know the laws of exponents.

## The Laws of Exponents

Let's start with the basic laws. These are special cases of a base with an exponent.
Law Explanation
Base of 1 14 = 1 × 1 × 1 × 1 = 1
Exponent of 0 Any base with an exponent of 0 is 1.
Exponent of 1 Any base with an exponent of 1 is equal to the base.
Exponent of −1 Any base with an exponent of −1 is equal to 1 divided by the base (the reciprocal of the base).
Read more about finding an exponent of −1 in algebra Let's look at the more complicated laws of exponents.

## Multiplying Powers When multiplying the same letter with exponents, add the exponents.
Example: a2 × a3 = a2 + 3 = a5
Read more about multiplying powers in algebra

## Dividing Powers When dividing the same letter with exponents, subtract the exponents.
Example: a5 ÷ a3 = a5 - 3 = a2
Read more about dividing powers in algbra

## Powers of a Power When raising one exponent to another, multiply the exponents.
Example: (a2)3 = a2 × 3 = a6
Read more about finding a power of a power in algebra

## Power of an Algebraic Fraction When raising a fraction to an exponent, raise both the numerator and denominator to the exponent.
Example: (a ⁄ b)2 = a2 ⁄ b2
Read more about finding the power of an algebraic fraction

## Exponent Is Negative A negative exponent means calculating the positive exponent and finding the reciprocal (i.e. find 1 over it).
Example: a−2 = 1 ⁄ a2
Read more about negative exponents in algebra

## Exponent Is a Fraction (Numerator is 1) A fractional exponent (where the fraction is 1 over n) means finding the nth root of the base. n = 2 is the square root.
n = 3 is the cube root.
Example: a½ = √a
Read more about how to find a fractional exponent in algebra

## Exponent Is a Fraction (Numerator is not 1) To find a fractional exponent (where the fraction is m over n), either:
• Find the mth power, and take the nth root, or
• Take the nth root, and find the mth power.
Example: a32 = √(a3) = (√a)3
Read more about how to find a fractional exponent in algebra

## Lesson Slides

The laws of exponents in algebra are often not used in isolation of each other, but are needed together. The slider below shows real examples of how to use the laws of exponents. Open the slider in a new tab

## What Is an Exponent?

An exponent tells you how many times a number or letter is multiplied by itself. An exponent is denoted by a raised number by the right hand side of the number (called the base) that is multiplied by itself. For example, a2 means that a is multiplied by itself 2 times:
a2 = a × a

## There Are No Rules for Adding or Subtracting Exponents

There are no rules for adding or subtracting exponents. They just stay as they are: Mathematics Monster has known some students who have got confused with other laws of exponents and have made up their own rules: The correct rules are: Just the exponents are added or subtracted.
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## See Also

What is algebra? What is an exponent? Finding a negative exponent in algebra Multiplying powers in algebra Dividing powers in algebra Finding a power of a fraction in algebra Finding a fractional exponent in algebra