Examples with solutions for Applying Combined Exponents Rules: Presenting powers with negative exponents as fractions

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

52 5^{-2}

Video Solution

Step-by-Step Solution

We use the property of powers of a negative exponent:

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

52=152=125 5^{-2}=\frac{1}{5^2}=\frac{1}{25}

Therefore, the correct answer is option d.

Answer

125 \frac{1}{25}

Exercise #3

[(17)1]4= [(\frac{1}{7})^{-1}]^4=

Video Solution

Step-by-Step Solution

We use the power property of a negative exponent:

an=1an a^{-n}=\frac{1}{a^n} We will rewrite the fraction in parentheses as a negative power:

17=71 \frac{1}{7}=7^{-1} Let's return to the problem, where we had:

((17)1)4=((71)1)4 \bigg( \big( \frac{1}{7}\big)^{-1}\bigg)^4=\big((7^{-1})^{-1} \big)^4 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:

((71)1)4=(711)4=(71)4=714=74 \big((7^{-1})^{-1} \big)^4 =(7^{-1\cdot-1})^4=(7^1)^4=7^{1\cdot4}=7^4 Therefore, the correct answer is option c

Answer

74 7^4

Exercise #4

41=? 4^{-1}=\text{?}

Video Solution

Step-by-Step Solution

We begin by using the power rule of negative exponents.

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

41=141=14 4^{-1}=\frac{1}{4^1}=\frac{1}{4} We can therefore deduce that the correct answer is option B.

Answer

14 \frac{1}{4}

Exercise #5

25=? 2^{-5}=\text{?}

Video Solution

Step-by-Step Solution

We begin by using the power rule of negative exponents.

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

25=125=132 2^{-5}=\frac{1}{2^5}=\frac{1}{32} We can therefore deduce that the correct answer is option A.

Answer

132 \frac{1}{32}

Exercise #6

(7)3=? (-7)^{-3}=\text{?}

Video Solution

Step-by-Step Solution

We begin by using the power property for a negative exponent:

bn=1bn b^{-n}=\frac{1}{b^n} We apply it to the problem:

(7)3=1(7)3 (-7)^{-3}=\frac{1}{(-7)^3} We then subsequently notice that each whole number inside the parentheses is raised to a negative power (that is, the number and its negative coefficient together) When using the previously mentioned power property: We are careful to take this into account,

We then continue by simplifying the expression in the denominator of the fraction, remembering the exponentiation property for the power of terms in multiplication:

(am)n=amn (a^m)^n=a^{m\cdot n} We apply the resulting expression

1(7)3=1(17)3=1(1)373=1173=173=173 \frac{1}{(-7)^3}=\frac{1}{(-1\cdot7)^3}=\frac{1}{(-1)^3\cdot7^3}=\frac{1}{-1\cdot7^3}=\frac{1}{-7^3}=-\frac{1}{7^3}

In summary we are able to deduce that the solution to the problem is as follows:

(7)3=1(7)3=173=173 (-7)^{-3}=\frac{1}{(-7)^3}=\frac{1}{-7^3}=-\frac{1}{7^3}

Therefore, the correct answer is option B.

Answer

173 -\frac{1}{7^{3}}

Exercise #7

724=? 7^{-24}=\text{?}

Video Solution

Step-by-Step Solution

Using the rules of negative exponents: how to raise a number to a negative exponent:

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

724=1724 7^{-24}=\frac{1}{7^{24}} Therefore, the correct answer is option D.

Answer

1724 \frac{1}{7^{24}}

Exercise #8

192=? 19^{-2}=\text{?}

Video Solution

Step-by-Step Solution

In order to solve the exercise, we use the negative exponent rule.

an=1an a^{-n}=\frac{1}{a^n}

We apply the rule to the given exercise:

192=1192 19^{-2}=\frac{1}{19^2}

We can then continue and calculate the exponent.

1192=1361 \frac{1}{19^2}=\frac{1}{361}

Answer

1361 \frac{1}{361}

Exercise #9

a4=? a^{-4}=\text{?}

(a0) (a\ne0)

Video Solution

Step-by-Step Solution

We begin by using the negative exponent rule.

bn=1bn b^{-n}=\frac{1}{b^n} We apply it to the problem:

a4=1a4 a^{-4}=\frac{1}{a^4} Therefore, the correct answer is option B.

Answer

1a4 \frac{1}{a^4}

Exercise #10

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 #11

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 #12

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 #13

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 #14

74=? 7^{-4}=\text{?}

Video Solution

Step-by-Step Solution

We must first remind ourselves of the negative exponent rule:

an=1an a^{-n}=\frac{1}{a^n} When applied to given the expression we obtain the following:

74=174=12401 7^{-4}=\frac{1}{7^4}=\frac{1}{2401}

Therefore, the correct answer is option C.

Answer

12401 \frac{1}{2401}

Exercise #15

(23)4=? (\frac{2}{3})^{-4}=\text{?}

Video Solution

Step-by-Step Solution

We use the formula:

(ab)n=(ba)n (\frac{a}{b})^{-n}=(\frac{b}{a})^n

Therefore, we obtain:

(32)4 (\frac{3}{2})^4

We use the formula:

(ba)n=bnan (\frac{b}{a})^n=\frac{b^n}{a^n}

Therefore, we obtain:

3424=3×3×3×32×2×2×2=8116 \frac{3^4}{2^4}=\frac{3\times3\times3\times3}{2\times2\times2\times2}=\frac{81}{16}

Answer

8116 \frac{81}{16}

Exercise #16

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 #17

7483(17)4=? 7^4\cdot8^3\cdot(\frac{1}{7})^4=\text{?}

Video Solution

Step-by-Step Solution

We use the formula:

(ab)n=anbn (\frac{a}{b})^n=\frac{a^n}{b^n}

We decompose the fraction inside of the parentheses:

(17)4=1474 (\frac{1}{7})^4=\frac{1^4}{7^4}

We obtain:

74×83×1474 7^4\times8^3\times\frac{1^4}{7^4}

We simplify the powers: 74 7^4

We obtain:

83×14 8^3\times1^4

Remember that the number 1 in any power is equal to 1, thus we obtain:

83×1=83 8^3\times1=8^3

Answer

83 8^3

Exercise #18

xa=? x^{-a}=\text{?}

Video Solution

Step-by-Step Solution

We use the exponential property of a negative exponent:

bn=1bn b^{-n}=\frac{1}{b^n} We apply it to the problem:

xa=1xa x^{-a}=\frac{1}{x^a} Therefore, the correct answer is option C.

Answer

1xa \frac{1}{x^a}

Exercise #19

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

Video Solution

Answer

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

Exercise #20

143=? \frac{1}{4^{-3}}=?

Video Solution

Answer

64 64