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# Powers (Bases and Exponents)

## What is an exponent?

An exponent indicates how many times the number must be multiplied by itself. Exponents are also referred to as powers or indices. Usually, the exponent is written as a superscript to the right of the base.

Consider the number 53

In this example, 5 is the base and 3 is the exponent. A base is a number that we will repeatedly multiply to itself, and the exponent will tell us how many times the base will be multiplied to itself. Thus, 53 means the same thing as 5 x 5 x 5.

• five raised to the power of three,
• five raised to three, and
• five to the power of three.

Exponentiation is a mathematical operation written in the form of xn, where x denotes the base and n represents the exponent.

## What is the origin of exponents?

The word power came from the Latin word potentia, potestas, dignitas which is a mistranslation of the ancient Greek term δύναμις (dúnamis), which was employed for the square of a line by Euclid, following Hippocrates of Chios.

Meanwhile, Archimedes discovered and proved the laws of exponents in his work The Sand Reckoner. In his work, he was able to prove 10a x 10b = 10a + b. During the 19th century, Muhammad ibn Mūsā al-Khwārizmī introduced the terms مَال (māl, “possessions”, “property”) for a square.

Jost Bürgi utilized exponents for Roman numerals in the late 16th century. In the 15th century, Nicolas Chuquet created a type of exponential notation that was later utilized by Henricus Grammateus and Michael Stifel in the 16th century. Michael Stifel created the term “exponent” in 1544. In 1696, Samuel Jeake introduced the term indices.

René Descartes established the first form of our contemporary exponential notation in his treatise titled La Géométrie in the early 17th century; the notation is introduced in Book I of the text.

Leonhard Euler proposed variable exponents and, implicitly, non-integer exponents in 1748 when he wrote:

“consider exponentials or powers in which the exponent itself is a variable. It is clear that quantities of this kind are not algebraic functions, since in those the exponents must be constant.”

## What are the laws of exponent?

To answer and solve problems involving exponents, the laws of exponents are fundamental. These rules are needed to be followed to be able to simplify formulas with exponents. Let’s take a look at the following rules we have for exponents!

### Product Rule

The product rule of exponents is used to multiply expressions that have the same bases. This rule states that for any non-zero term a where m and n are real numbers

am x an = am + n

This means that, to get the product of an exponent that have the same base, we are going to simply copy the base and add their exponents.

Example #1

What is the product of 52 and 53

Solution

Example #2

Find the product of a and a6.

Solution

Example #3

Find the product of x3y and x3y2.

Solution

### Quotient Rule

The quotient rule of exponents is used to simplify algebraic terms or expressions that have the same bases. This rule states that for any non-zero term a where m and n are real numbers,

$\frac{a^m}{a^n}= a^{m – n}$

This means that, to get the quotient of an exponent that has the same base, we are going to simply copy the base and subtract the exponent of the numerator by the exponent of the denominator.

Example #1

What is the quotient if 97 is divided by 93

Solution

Example #2

Determine the quotient if a10 is divided by a7.

Solution

Example #3

Find the quotient if x4y3 is divided by xy2.

Solution

### Zero Exponent Rule

The zero exponent rule is used to simplify algebraic terms or expressions that have an exponent of zero. This rule simply states that if the exponent of any non-zero base a is zero, then it is always equal to 1.

a0= 1

Example #1

What is the equivalent of 30

Solution

Example #2

Determine the value of a0

Solution

Example #3

Find the equivalent of x0y0

Solution

### Negative Exponent Rule

The negative exponent rule is used to simplify algebraic terms or expressions that have a negative exponent. This rule states that if the exponent of any non-zero base a is negative, we need to convert it to a positive exponent by getting its reciprocal.

$a^{-m}= \frac{1}{a^m}$

Similarly,

$\frac{1}{a^{-m}} = a^{m}$

Example #1

What is the equivalent of 2-4

Solution

Example #2

Simplify a-2

Solution

Example #3

What is the equivalent of $\frac{x^{-3}}{y^{-4}}$?

Solution

### Power of a Power Rule

The power of a power rule is used to simplify algebraic terms where the exponent of the base is raised to another exponent, we will get the product of the two exponents. This rule states that if a non-zero term a and m and n are integers,

(am)n= amn

Example #1

Simplify (43)2

Solution

Example #2

Simplify (a3)7

Solution

### Power of a Product Rule

The power of a product rule is used to simplify algebraic terms with more than one variable that is being multiplied together and raised to an exponent. This rule states that if a non-zero term a and b and m is an integer,

(ab)m= ambm

Example #1

Simplify (ab)8

Solution

Example #2

Simplify (x4y5)3

Solution

### Power of a Quotient Rule

The power of a quotient rule is used to simplify the quotient of an algebraic term with more than one variable by simply distributing the exponent to the numerator and the denominator. This rule states that if a non-zero term a and b where m is an integer,

$(\frac{a}{b})^{m}= \frac{a^m}{b^m}$

Example #1

Simplify $(\frac{4}{5})^2$ .

Solution

Example #2

Simplify $(\frac{a^7}{b^6})^4$

Solution

Example #3

Simplify $(\frac{x^3y^2}{wz^5})^6$

Solution

## What are the common misconceptions in exponents?

When it comes to simplifying exponents, students commit errors that will result to a wrong answer. Some of these errors are listed below:

• Multiplying the base and exponent. Usually, students simply multiply the base to the number written on the exponent.

Incorrect: 34 ≠3 x 4

Correct: 33 = 3 x 3 x 3 x 3

• Applying the power of the product rule wrong. Some students distribute the exponent even though it is not a product of two or more variables.

Incorrect: (4 + 5)2 ≠ 42 + 52

Correct: (4 + 5)2 = (9)2 = 81

## What is the significance of exponents?

Exponents are usually used as a shortcut to represent a number that is repeatedly multiplied by itself. Most of the time, we don’t really see or use exponents in our everyday lives, but they are very significant, especially in the sciences.

Exponents are used in showing square or cubic measurements such as square feet (ft2), square meters (m2), square inches (in2), square miles (mi2), cubic feet (ft3), cubic meters (m3). With the help of exponents, it is easier for us to distinguish square and cubic measurements. Taking measurements and calculating multi-dimensional quantities is one of the most prevalent real-world applications of exponents. Because area is a two-dimensional measure of space (length x breadth), it is always measured in square units such as square feet or square meters.

Scientists use exponents to show extraordinarily large or small numbers. With the help of exponents, writing numbers in a scientific notation became possible. In scientific notation, 150 000 can be written as 1.5 x 105 – which translates to 1.5 x 10 x 10 x 10 x 10 x 10.

Exponents are of great importance in any scientific measurement that uses a scale such as pH scale and Richter scale. The pH scale and the Richter scale are both logarithmic scales, with each whole number denoting a ten-fold rise over the previous value.

Say, for example, a scientist knows that a material with a pH of 4 indicates 104, but a substance with a pH of 8 represents 105. This suggests that a substance with a pH of 5 is ten times more basic than one with a pH of 4.
Exponents are also used in computer language. We frequently hear the terms megabytes, gigabytes, and terabytes. “Mega” refers to 106 or one million, “giga” refers to 109, and “tera” refers to 1012. More so, the prefixes mega- and giga- are also used in other domains such as megahertz indicates 106 or one million hertz.