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

Exercise #1

(0.25)2=? (0.25)^{-2}=\text{?}

Video Solution

Step-by-Step Solution

First, let's convert the decimal fraction in the problem to a simple fraction:

0.25=25100=14 0.25=\frac{25}{100}=\frac{1}{4}

where we remembered that 0.25 is 25 hundredths, meaning:

251100=25100 25\cdot\frac{1}{100}=\frac{25}{100}

If so, let's write the problem:

(0.25)2=(14)2=? (0.25)^{-2}=\big(\frac{1}{4}\big)^{-2}=\text{?}

Now we'll use the negative exponent law:

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

and deal with the fraction expression inside the parentheses:

(14)2=(41)2 \big(\frac{1}{4}\big)^{-2}=(4^{-1})^{-2}

when we applied the above exponent law to the expression inside the parentheses,

Next, we'll recall the power of a power law:

(am)n=amn (a^m)^n=a^{m\cdot n}

and we'll apply this law to the expression we got in the last step:

(41)2=4(1)(2)=42=16 (4^{-1})^{-2}=4^{(-1)\cdot(-2)}=4^2=16

where in the first step we carefully applied the above law and used parentheses in the exponent to perform the multiplication between the powers, then we simplified the resulting expression, and finally calculated the numerical result from the last step.

Let's summarize the solution steps:

(0.25)2=(14)2=4(1)(2)=16 (0.25)^{-2}=\big(\frac{1}{4}\big)^{-2}=4^{(-1)\cdot(-2)}=16

Therefore, the correct answer is answer B.

Answer

16 16

Exercise #2

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 #3

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 #4

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 #5

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 #6

454614=? 4^5-4^6\cdot\frac{1}{4}=\text{?}

Video Solution

Step-by-Step Solution

We'll use the law of exponents for negative exponents, but in the opposite direction:

1an=an \frac{1}{a^n} =a^{-n} Let's apply this law to the problem:

454614=454641 4^5-4^6\cdot\frac{1}{4}= 4^5-4^6\cdot4^{-1} When we apply the above law to the second term from the left in the sum, and convert the fraction to a term with a negative exponent,

Next, we'll use the law of exponents for multiplying terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n} Let's apply this law to the expression we got in the last step:

454641=4546+(1)=45461=4545=0 4^5-4^6\cdot4^{-1} =4^5-4^{6+(-1)}=4^5-4^{6-1}=4^5-4^{5}=0 When we apply the above law of exponents to the second term from the left in the expression we got in the last step, then we'll simplify the resulting expression,

Let's summarize the solution steps:

454614=454641=4545=0 4^5-4^6\cdot\frac{1}{4}= 4^5-4^6\cdot4^{-1} =4^5-4^{5}=0

We got that the answer is 0,

Therefore the correct answer is answer A.

Answer

0

Exercise #7

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 #8

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

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:

(5)3=1(5)3 (-5)^{-3}=\frac{1}{(-5)^3} Next let's recall the power rule for expressions in parentheses:

(xy)n=xnyn (x\cdot y)^n=x^n\cdot y^n And we'll apply it to the denominator of the expression we received:

1(5)3=1(15)3=1(1)353=1153=153=1125 \frac{1}{(-5)^3}=\frac{1}{(-1\cdot5)^3}=\frac{1}{(-1)^3\cdot5^3}=\frac{1}{-1\cdot5^3}=-\frac{1}{5^3}=-\frac{1}{125} In the first step, we expressed the negative number inside the parentheses in the denominator as a multiplication between a positive number and negative one, and then we used the power rule for expressions in parentheses to expand the parentheses, and then we simplified the expression.

Let's summarize the solution to the problem:

(5)3=1(5)3=153=1125 (-5)^{-3}=\frac{1}{(-5)^3} =\frac{1}{-5^3}=-\frac{1}{125}

Therefore, the correct answer is answer B.

Answer

1125 -\frac{1}{125}

Exercise #9

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 #10

(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 #11

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 #12

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 #13

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 #14

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

Video Solution

Step-by-Step Solution

First, let's note that:

a.

10=52 10=5\cdot2

For this, we'll recall the law of exponents for multiplication in parentheses:

(ab)n=anbn (a\cdot b)^n=a^n\cdot b^n

According to this, we get that:

(5)3=(15)3=(1)353=153=53 (-5)^3=(-1\cdot5)^3=(-1)^3\cdot5^3=-1\cdot5^3=-5^3

We want to use the understanding in 'a' to get terms with identical bases in the numerator and denominator,

Let's return to the problem and apply the understandings from 'a' and 'b':

10(5)3=2553=21553=2553 \frac{10}{(-5)^3}=\frac{2\cdot5}{-5^3}=\frac{2}{-1}\cdot\frac{5}{5^3}=-2\cdot\frac{5}{5^3}

Where in the first stage we used 'a' in the numerator and 'b' in the fraction's denominator, in the next stage we presented the fraction as a multiplication of fractions according to the rule for multiplying fractions, then we simplified the first fraction in the multiplication.

Now we'll use the law of exponents for division between terms with identical bases:

aman=amn \frac{a^m}{a^n}=a^{m-n}

Let's apply this law to the expression we got:

2553=2513=252 -2\cdot\frac{5}{5^3}=-2\cdot5^{1-3}=-2\cdot5^{-2}

where in the first stage we applied this law to the fraction in the multiplication and then simplified the expression we got,

Let's summarize the solution steps:

10(5)3=2553=252 \frac{10}{(-5)^3} =-2\cdot\frac{5}{5^3} =-2\cdot5^{-2}

Therefore, the correct answer is answer b.

Answer

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

Exercise #15

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 #16

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 #17

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 #18

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

Video Solution

Step-by-Step Solution

First let's recall the negative exponent rule:

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

143=4(3)=43=64 \frac{1}{4^{-3}}=4^{-(-3)}=4^3=64 In the first stage, we carefully applied the above exponent rule, and since the term in the denominator is already a negative exponent, when using the mentioned rule we put the exponent of the term that was in the denominator in parentheses (this is to apply the minus sign associated with the exponent rule later), then we simplified the exponent expression that was obtained.

In the final stage, we calculated the actual numerical result of the expression we received.

Therefore, the correct answer is answer B.

Answer

64 64

Exercise #19

[(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 #20

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}