Examples with solutions for Negative Exponents: Presenting powers in the denominator as powers with negative exponents

Exercise #1

(14)1 (\frac{1}{4})^{-1}

Video Solution

Step-by-Step Solution

We use the power property for a negative exponent:

an=1an a^{-n}=\frac{1}{a^n} We will write the fraction in parentheses as a negative power with the help of the previously mentioned power:

14=141=41 \frac{1}{4}=\frac{1}{4^1}=4^{-1} We return to the problem, where we obtained:

(14)1=(41)1 \big(\frac{1}{4}\big)^{-1}=(4^{-1})^{-1} We continue and use the power property of an exponent raised to another exponent:

(am)n=amn (a^m)^n=a^{m\cdot n} And we apply it in the problem:

(41)1=411=41=4 (4^{-1})^{-1}=4^{-1\cdot-1}=4^1=4 Therefore, the correct answer is option d.

Answer

4 4

Exercise #2

183=? \frac{1}{8^3}=\text{?}

Video Solution

Step-by-Step Solution

We use the negative exponent rule.

bn=1bn b^{-n}=\frac{1}{b^n}

We apply it to the problem in the opposite sense.:

183=83 \frac{1}{8^3}=8^{-3}

Therefore, the correct answer is option A.

Answer

83 8^{-3}

Exercise #3

129=? \frac{1}{2^9}=\text{?}

Video Solution

Step-by-Step Solution

We use the power property for a negative exponent:

an=1an a^{-n}=\frac{1}{a^n} We apply it to the given expression:

129=29 \frac{1}{2^9}=2^{-9}

Therefore, the correct answer is option A.

Answer

29 2^{-9}

Exercise #4

1123=? \frac{1}{12^3}=\text{?}

Video Solution

Step-by-Step Solution

To begin with, we must remind ourselves of the Negative Exponent rule:

an=1an a^{-n}=\frac{1}{a^n} We apply it to the given expression :

1123=123 \frac{1}{12^3}=12^{-3} Therefore, the correct answer is option A.

Answer

123 12^{-3}

Exercise #5

1(2)7=? \frac{1}{(-2)^7}=?

Video Solution

Step-by-Step Solution

To begin with we deal with the expression in the denominator of the fraction. Making note of the power rule for exponents (raising an exponent to another exponent):

(am)n=amn (a^m)^n=a^{m\cdot n} We obtain the following:

(2)7=(12)7=(1)727=127=27 (-2)^7=(-1\cdot2)^7=(-1)^7\cdot2^7=-1\cdot2^7=-2^7

We then return to the initial problem and apply the above information:

1(2)7=127=11127=127 \frac{1}{(-2)^7}=\frac{1}{-2^7}=\frac{1}{-1}\cdot\frac{1}{2^7}=-\frac{1}{2^7}

In the last step we remember that:

11=1 \frac{1}{-1}=-1

Next, we remember the Negative Exponent rule ( raising exponents to a negative power)

an=1an a^{-n}=\frac{1}{a^n} We apply it to the expression we obtained in the last step:

127=27 -\frac{1}{2^7}=-2^{-7} Let's summarize the steps of the solution:

1(2)7=127=27 \frac{1}{(-2)^7}=-\frac{1}{2^7} = -2^{-7}

Therefore, the correct answer is option C.

Answer

(2)7 (-2)^{-7}

Exercise #6

105=? 10^{-5}=?

Video Solution

Step-by-Step Solution

First, let's recall the negative exponent rule:

bn=1bn b^{-n}=\frac{1}{b^n} We'll apply it to the expression we received:

105=1105=1100000=0.00001 10^{-5}=\frac{1}{10^5}=\frac{1}{100000}=0.00001 In the final steps, we performed the exponentiation in the numerator and then wrote the answer as a decimal.

Therefore, the correct answer is option A.

Answer

0.00001 0.00001

Exercise #7

1an=? \frac{1}{a^n}=\text{?}

a0 a\ne0

Video Solution

Answer

an a^{-n}

Exercise #8

2738=? \frac{27}{3^8}=\text{?}

Video Solution

Answer

35 3^{-5}

Exercise #9

242=? \frac{2}{4^{-2}}=\text{?}

Video Solution

Answer

242 2\cdot4^2

Exercise #10

10(5)3=? \frac{10}{(-5)^3}=\text{?}

Video Solution

Answer

2(5)2 -2(-5)^{-2}