Simplify expressions with exponents equal to zero.
Simplify expressions with negative exponents.
Simplify exponential expressions.
Return to the quotient rule. We made the condition that m>n so that the difference m−n would never be zero or negative. What would happen if m=n? In this case, we would use the zero exponent rule of exponents to simplify the expression to 1. To see how this is done, let us begin with an example.
t8t8=t8t8=1
If we were to simplify the original expression using the quotient rule, we would have
t8t8=t8−8=t0
If we equate the two answers, the result is t0=1. This is true for any nonzero real number, or any variable representing a real number.
a0=1
The sole exception is the expression 00. This appears later in more advanced courses, but for now, we will consider the value to be undefined.
A General Note: The Zero Exponent Rule of Exponents
For any nonzero real number a, the zero exponent rule of exponents states that
a0=1
using order of operations with fractions
When simplifying expressions with exponents, it is sometimes helpful to rely on the rule for multiplying fractions to separate the factors before doing work on them. For example, to simplify the expression amz5amz2 using exponent rules, you may find it helpful to break the fraction up into a product of fractions, then simplify.
amz5amz2=5⋅amam⋅zz2=5⋅am−m⋅z2−1=5⋅a0⋅z1=5z
Example: Using the Zero Exponent Rule
Simplify each expression using the zero exponent rule of exponents.
c3c3
x5−3x5
(j2k)⋅(j2k)3(j2k)4
(rs2)25(rs2)2
Answer:
Use the zero exponent and other rules to simplify each expression.
Simplify each expression using the zero exponent rule of exponents.
t7t7
2(de2)11(de2)11
w6w4⋅w2
t2⋅t5t3⋅t4
Answer:
1
21
1
1
[embed]
[embed]
In this video we show more examples of how to simplify expressions with zero exponents.
https://youtu.be/rpoUg32utlc
Using the Negative Rule of Exponents
Another useful result occurs if we relax the condition that m>n in the quotient rule even further. For example, can we simplify h5h3? When m<n—that is, where the difference m−n is negative—we can use the negative rule of exponents to simplify the expression to its reciprocal.
Divide one exponential expression by another with a larger exponent. Use our example, h5h3.
Putting the answers together, we have h−2=h21. This is true for any nonzero real number, or any variable representing a nonzero real number.
A factor with a negative exponent becomes the same factor with a positive exponent if it is moved across the fraction bar—from numerator to denominator or vice versa.
a−n=an1 and an=a−n1
We have shown that the exponential expression an is defined when n is a natural number, 0, or the negative of a natural number. That means that an is defined for any integer n. Also, the product and quotient rules and all of the rules we will look at soon hold for any integer n.
A General Note: The Negative Rule of Exponents
For any nonzero real number a and natural number n, the negative rule of exponents states that
a−n=an1 and an=a−n1
Example: Using the Negative Exponent Rule
Write each of the following quotients with a single base. Do not simplify further. Write answers with positive exponents.
θ10θ3
z4z2⋅z
(−5t3)8(−5t3)4
Answer:
θ10θ3=θ3−10=θ−7=θ71
z4z2⋅z=z4z2+1=z4z3=z3−4=z−1=z1
(−5t3)8(−5t3)4=(−5t3)4−8=(−5t3)−4=(−5t3)41
Try It
Write each of the following quotients with a single base. Do not simplify further. Write answers with positive exponents.
(−3t)8(−3t)2
f49⋅ff47
5k72k4
Answer:
(−3t)61
f31
5k32
[embed]
[embed]
[embed]
Watch this video to see more examples of simplifying expressions with negative exponents.
https://youtu.be/Gssi4dBtAEI
Example: Using the Product and Quotient Rules
Write each of the following products with a single base. Do not simplify further. Write answers with positive exponents.
Write each of the following products with a single base. Do not simplify further. Write answers with positive exponents.
t−11⋅t6
25132512
Answer:
t−5=t51
251
[embed]
Finding the Power of a Product
To simplify the power of a product of two exponential expressions, we can use the power of a product rule of exponents, which breaks up the power of a product of factors into the product of the powers of the factors. For instance, consider (pq)3. We begin by using the associative and commutative properties of multiplication to regroup the factors.
A General Note: The Power of a Product Rule of Exponents
For any real numbers a and b and any integer n, the power of a product rule of exponents states that
(ab)n=anbn
Example: Using the Power of a Product Rule
Simplify each of the following products as much as possible using the power of a product rule. Write answers with positive exponents.
(ab2)3
(2t)15
(−2w3)3
(−7z)41
(e−2f2)7
Answer:
Use the product and quotient rules and the new definitions to simplify each expression.
(ab2)3=(a)3⋅(b2)3=a1⋅3⋅b2⋅3=a3b6
2t15=(2)15⋅(t)15=215t15=32,768t15
(−2w3)3=(−2)3⋅(w3)3=−8⋅w3⋅3=−8w9
(−7z)41=(−7)4⋅(z)41=2,401z41
(e−2f2)7=(e−2)7⋅(f2)7=e−2⋅7⋅f2⋅7=e−14f14=e14f14
Try It
Simplify each of the following products as much as possible using the power of a product rule. Write answers with positive exponents.
(g2h3)5
(5t)3
(−3y5)3
(a6b7)31
(r3s−2)4
Answer:
g10h15
125t3
−27y15
a18b211
s8r12
[embed]
[embed]
[embed]
In the following video we show more examples of how to find the power of a product.
https://youtu.be/p-2UkpJQWpo
Finding the Power of a Quotient
To simplify the power of a quotient of two expressions, we can use the power of a quotient rule, which states that the power of a quotient of factors is the quotient of the powers of the factors. For example, let’s look at the following example.
(e−2f2)7=e14f14
Let’s rewrite the original problem differently and look at the result.
Simplify each of the following quotients as much as possible using the power of a quotient rule. Write answers with positive exponents.
(cb5)3
(u85)4
(w3−1)35
(p−4q3)8
(c−5d−3)4
Answer:
c3b15
u32625
w105−1
p32q24
c20d121
[embed]
[embed]
[embed]
Simplifying Exponential Expressions
Recall that to simplify an expression means to rewrite it by combing terms or exponents; in other words, to write the expression more simply with fewer terms. The rules for exponents may be combined to simplify expressions.
Example: Simplifying Exponential Expressions
Simplify each expression and write the answer with positive exponents only.
(6m2n−1)3
175⋅17−4⋅17−3
(v−1u−1v)2
(−2a3b−1)(5a−2b2)
(x22)4(x22)−4
(6w−2)2(3w2)5
Answer:
\begin{align} {\left(6{m}^{2}{n}^{-1}\right)}^{3}& = {\left(6\right)}^{3}{\left({m}^{2}\right)}^{3}{\left({n}^{-1}\right)}^{3}&& \text{The power of a product rule} \\ & = {6}^{3}{m}^{2\cdot 3}{n}^{-1\cdot 3}&& \text{The power rule} \\ & = 216{m}^{6}{n}^{-3}&& \text{Simplify}. \\ & = \frac{216{m}^{6}}{{n}^{3}}&& \text{The negative exponent rule} \end{align}
\begin{align} \frac{{\left(3{w}^{2}\right)}^{5}}{{\left(6{w}^{-2}\right)}^{2}}& = \frac{{\left(3\right)}^{5}\cdot {\left({w}^{2}\right)}^{5}}{{\left(6\right)}^{2}\cdot {\left({w}^{-2}\right)}^{2}}&& \text{The power of a product rule} \\ & = \frac{{3}^{5}{w}^{2\cdot 5}}{{6}^{2}{w}^{-2\cdot 2}}&& \text{The power rule} \\ & = \frac{243{w}^{10}}{36{w}^{-4}} && \text{Simplify}. \\ & = \frac{27{w}^{10-\left(-4\right)}}{4}&& \text{The quotient rule and reduce fraction} \\ & = \frac{27{w}^{14}}{4}&& \text{Simplify}. \end{align}
Try It
Simplify each expression and write the answer with positive exponents only.
(2uv−2)−3
x8⋅x−12⋅x
(f−1e2f−3)2
(9r−5s3)(3r6s−4)
(94tw−2)−3(94tw−2)3
(7h−1k2)2(2h2k)4
Answer:
8u3v6
x31
f4e4
s27r
1
4916h10
[embed]
[embed]
[embed]
[embed]
In the following video we show more examples of how to find the power of a quotient.
https://youtu.be/BoBe31pRxFM
Licenses & Attributions
CC licensed content, Original
Revision and Adaptation.Provided by: Lumen LearningLicense: CC BY: Attribution.
CC licensed content, Shared previously
College Algebra.Provided by: OpenStaxAuthored by: Abramson, Jay et al..License: CC BY: Attribution. License terms: Download for free at http://cnx.org/contents/9b08c294-057f-4201-9f48-5d6ad992740d@5.2.
Simplify Expressions With Negative Exponents.Authored by: James Sousa (Mathispower4u.com).License: CC BY: Attribution.
Power of a Product.Authored by: James Sousa (Mathispower4u.com).License: CC BY: Attribution.
Power of a Quotient.Authored by: James Sousa (Mathispower4u.com).License: CC BY: Attribution.
Question ID 44120, 43231.Authored by: Brenda Gardner.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 7833, 14060.Authored by: Tyler Wallace.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 109762, 109765.Authored by: Lumen Learning.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 51959.Authored by: Roy Shahbazian.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 93393.Authored by: Michael Jenck.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 14047, 14058, 14059, 14046, 14051, 14056, 14057.Authored by: James Souza.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
Question ID 43896.Authored by: Carla Kulinsky.License: CC BY: Attribution. License terms: IMathAS Community License CC-BY + GPL.
CC licensed content, Specific attribution
College Algebra.Provided by: OpenStaxAuthored by: OpenStax College Algebra.Located at: https://cnx.org/contents/9b08c294-057f-4201-9f48-5d6ad992740d@3.278:1/Preface.License: CC BY: Attribution.