Examples with solutions for Applying Combined Exponents Rules: Calculating powers with negative exponents

Exercise #1

(8×9×5×3)2= (8\times9\times5\times3)^{-2}=

Video Solution

Step-by-Step Solution

We begin by applying the power rule to the products within the parentheses:

(zt)n=zntn (z\cdot t)^n=z^n\cdot t^n

That is, the power applied to a product within parentheses is applied to each of the terms when the parentheses are opened,

We apply the rule to the given problem:

(8953)2=82925232 (8\cdot9\cdot5\cdot3)^{-2}=8^{-2}\cdot9^{-2}\cdot5^{-2}\cdot3^{-2}

Therefore, the correct answer is option c.

Note:

Whilst it could be understood that the above power rule applies only to two terms of the product within parentheses, in reality, it is also valid for the power over a multiplication of multiple terms within parentheses, as was seen in the above problem.

A good exercise is to demonstrate that if the previous property is valid for a power over a product of two terms within parentheses (as formulated above), then it is also valid for a power over several terms of the product within parentheses (for example - three terms, etc.).

Answer

82×92×52×32 8^{-2}\times9^{-2}\times5^{-2}\times3^{-2}

Exercise #2

(3×2×4×6)4= (3\times2\times4\times6)^{-4}=

Video Solution

Step-by-Step Solution

We begin by using the power rule for parentheses.

(zt)n=zntn (z\cdot t)^n=z^n\cdot t^n

That is, the power applied to a product inside parentheses is applied to each of the terms within when the parentheses are opened,

We apply the above rule to the given problem:

(3246)4=34244464 (3\cdot2\cdot4\cdot6)^{-4}=3^{-4}\cdot2^{-4}\cdot4^{-4}\cdot6^{-4}

Therefore, the correct answer is option d.

Note:

According to the formula of the power property inside parentheses mentioned above, it might seem as though it refers to only two terms of the product inside of the parentheses, but in reality, it is also valid for the power over a multiplication of many terms inside parentheses, as was seen above.

A good exercise is to demonstrate that if the previous property is valid for a power over a product of two terms inside parentheses (as formulated above), then it is also valid for a power over several terms of the product inside parentheses (for example - three terms, etc.).

Answer

34×24×44×64 3^{-4}\times2^{-4}\times4^{-4}\times6^{-4}

Exercise #3

Solve the following problem:

((7×3)2)6+(31)3×(23)4= ((7\times3)^2)^6+(3^{-1})^3\times(2^3)^4=

Video Solution

Step-by-Step Solution

Let's handle each expression in the problem separately:

a. We'll start with the leftmost expression, first calculating the result of the multiplication in parentheses, and then using the power rule for power to a power:

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

Let's apply this to the problem for the first expression from the left:

((73)2)6=(212)6=2126=2112 ((7\cdot3)^2)^6=(21^2)^6=21^{2\cdot6}=21^{12}

In the final step we calculated the result of multiplication in the power expression.

We're now finished with this expression, let's move on to the next expression from the left.

b. Continue with the second expression from the left, using the power rule for power to a power that we mentioned above and apply it separately to each factor in this expression:

(31)3(23)4=313234=33212 (3^{-1})^3\cdot(2^3)^4=3^{-1\cdot3}\cdot2^{3\cdot4}=3^{-3}\cdot2^{12}

Note that the multiplication factors that we obtained have different bases, thus we cannot further simplify this expression,

Therefore, let's combine parts a and b above in the result of the original problem:

((73)2)6+(31)3(23)4=2112+33212 ((7\cdot3)^2)^6+(3^{-1})^3\cdot(2^3)^4=21^{12}+3^{-3}\cdot2^{12}

The correct answer is answer d.

Answer

2112+33×212 21^{12}+3^{-3}\times2^{12}

Exercise #4

Simplify the following expression:

c1d6d2c3c2= c^{-1}\cdot d^6\cdot d^{-2}\cdot c^3\cdot c^2=

Video Solution

Step-by-Step Solution

Apply the power rule for multiplying terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n}

Note that this rule is valid only for terms with identical bases,

Here in the problem there are also terms with negative exponents, but this doesn't pose an issue regarding the use of the aforementioned power rule. In fact, this power rule is valid in all cases for numerical terms with different powers, including negative powers, rational number powers, and even irrational number powers, etc.

Let's return to the problem,

Note that there are two types of terms in the problem that differ from each other with different bases. First, we'll apply the commutative law of multiplication to arrange the expression so that all terms with the same base are adjacent, let's get to work:

c1d6d2c3c2=c1c3c2d6d2 c^{-1}\cdot d^6\cdot d^{-2}\cdot c^3\cdot c^2=c^{-1}\cdot c^3\cdot c^2\cdot d^6\cdot d^{-2}

Then we'll proceed to apply the aforementioned power rule separately to each different type of term,

c1c3c2d6d2=c1+3+2d6+(2)=c1+3+2d62=c4d4 c^{-1}\cdot c^3\cdot c^2\cdot d^6\cdot d^{-2}=c^{-1+3+2}\cdot d^{6+(-2)}=c^{-1+3+2}\cdot d^{6-2}=c^4\cdot d^4

To summarise we applied the above rule separately - for terms with base c c and for terms with base d d and then combined the powers in the exponent when we grouped all terms with the same base together.

Therefore, the correct answer is B.

Answer

c4d4 c^4\cdot d^4

Exercise #5

E6F4E0F7E= E^6\cdot F^{-4}\cdot E^0\cdot F^7\cdot E=

Video Solution

Step-by-Step Solution

We use the power property to multiply terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n} It should be noted that this property is only valid for terms with identical bases,

We return to the problem

We notice that in the problem there are two types of terms with different bases. First, for the sake of order, we will use the substitution property of multiplication to rearrange the expression so that the two terms with the same base are grouped together. Then, we will proceed to work:

E6F4E0F7E=E6E0EF4F7 E^6\cdot F^{-4}\cdot E^0\cdot F^7\cdot E=E^6\cdot E^0\cdot E\cdot F^{-4}\cdot F^7 Next, we apply the power property for each type of term separately,

E6E0EF4F7=E6+0+1F4+7=E7F3 E^6\cdot E^0\cdot E\cdot F^{-4}\cdot F^7=E^{6+0+1}\cdot F^{-4+7}=E^7\cdot F^3

We apply the power property separately - for the terms whose bases areE E and for the terms whose bases areF F and we add the exponents and simplify the terms with the same base.

The correct answer is then option d.

Note:

We use the fact that:

E=E1 E=E^1 .

Answer

E7F3 E^7\cdot F^3

Exercise #6

(3a)2=? (3a)^{-2}=\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 given expression and obtain the following:

(3a)2=1(3a)2 (3a)^{-2}=\frac{1}{(3a)^2} We then use the power rule for parentheses:

(xy)n=xnyn (x\cdot y)^n=x^n\cdot y^n We apply it to the denominator of the expression and obtain the following:

1(3a)2=132a2=19a2 \frac{1}{(3a)^2}=\frac{1}{3^2a^2}=\frac{1}{9a^2} Let's summarize the solution to the problem:

(3a)2=1(3a)2=19a2 (3a)^{-2}=\frac{1}{(3a)^2} =\frac{1}{9a^2}

Therefore, the correct answer is option A.

Answer

19a2 \frac{1}{9a^2}

Exercise #7

(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 #8

[(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 #9

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 #10

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 #11

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 #12

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 #13

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 #14

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 #15

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 #16

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 #17

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 #18

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 #19

53+5353=? 5^3+5^{-3}\cdot5^3=\text{?}

Video Solution

Step-by-Step Solution

We'll use the power rule for multiplication between terms with identical bases:

aman=am+n a^m\cdot a^n=a^{m+n} and we'll simplify the second term on the left in the equation using it:
53+5353=53+53+3=53+50=53+1 5^3+5^{-3}\cdot5^3=5^3+5^{-3+3}=5^3+5^0=5^3+1 where in the first stage we applied the mentioned rule to the second term on the left, then we simplified the expression with the exponent, and in the final stage we used the fact that any number raised to the power of 0 equals 1,

We didn't touch the first term of course since it was already simplified,

Therefore the correct answer is answer C.

Answer

53+1 5^3+1

Exercise #20

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