Powers - Special Cases

Powers of negative numbers

When we have an exponent on a negative number, we can get a positive result or a negative result.
We will know this based on the exponent – whether it is even or odd.

Powers with exponent \(0\)

Any number with an exponent of 00 will be equal to 11. (Except for 00)
No matter which number we raise to the power of 00, we will always get a result of 1.

Powers with negative integer exponents

In an exercise where we have a negative exponent, we turn the term into a fraction where:
the numerator will be 11 and in the denominator, the base of the exponent with the positive exponent.

Practice Powers - special cases

Examples with solutions for Powers - special cases

Exercise #1

50= 5^0=

Video Solution

Step-by-Step Solution

We use the power property:

X0=1 X^0=1 We apply it to the problem:

50=1 5^0=1 Therefore, the correct answer is C.

Answer

1 1

Exercise #2

(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 #3

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 #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

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 #6

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 #7

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 #8

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 #9

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 #10

1120=? 112^0=\text{?}

Video Solution

Step-by-Step Solution

We use the zero exponent rule.

X0=1 X^0=1 We obtain

1120=1 112^0=1 Therefore, the correct answer is option C.

Answer

1

Exercise #11

(8)2= (-8)^2=

Video Solution

Step-by-Step Solution

When we have a negative number raised to a power, the location of the minus sign is very important.

If the minus sign is inside or outside the parentheses, the result of the exercise can be completely different.

 

When the minus sign is inside the parentheses, our exercise will look like this:

(-8)*(-8)=

Since we know that minus times minus is actually plus, the result will be positive:

(-8)*(-8)=64

 

Answer

64 64

Exercise #12

[(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 #13

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 #14

(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 #15

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}