Evaluate 9⁴ × 3⁻⁸ × (1/3): Complete Exponent Simplification

Exponent Rules with Base Conversion

Solve the following problem:

943813=? 9^4\cdot3^{-8}\cdot\frac{1}{3}=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the following problem
00:03 Let's break down 9 to 3 squared
00:06 Let's substitute this into our exercise
00:13 Number (A) raised to a negative power (N)
00:17 Equals 1 divided by the number (A) raised to the same exponent (N)
00:23 We'll apply this formula to our exercise to convert a fraction into a base
00:28 When there's a power over a power, the combined power is the product of the powers
00:34 We'll apply this formula to our exercise
00:42 Let's calculate the powers
00:47 When multiplying powers with equal bases
00:50 The power of the result equals the sum of the powers
00:53 We'll apply this formula to our exercise
00:57 Let's calculate the power
01:00 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following problem:

943813=? 9^4\cdot3^{-8}\cdot\frac{1}{3}=\text{?}

2

Step-by-step solution

First let's note that the number 9 is a power of the number 3:

9=32 9=3^2

Therefore we can immediately move to a unified base in the problem, in addition we'll recall the law of powers for negative exponents but in the opposite direction:

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

Let's apply this to the problem:

943813=(32)43831 9^4\cdot3^{-8}\cdot\frac{1}{3}=(3^2)^4\cdot3^{-8}\cdot3^{-1}

In the first term of the multiplication we replaced the number 9 with a power of 3, according to the relationship mentioned earlier, and simultaneously the third term in the multiplication we expressed as a term with a negative exponent according to the aforementioned law of exponents.

Now let's recall two additional laws of exponents:

a. The law of exponents for power of a power:

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

b. The law of exponents for multiplication between terms with equal bases:

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

Let's apply these two laws to the expression we got in the last stage:

(32)43831=3243831=383831=38+(8)+(1)=3881=31 (3^2)^4\cdot3^{-8}\cdot3^{-1}=3^{2\cdot4}\cdot3^{-8}\cdot3^{-1}=3^8\cdot3^{-8}\cdot3^{-1}=3^{8+(-8)+(-1)}=3^{8-8-1}=3^{-1}

In the first stage we applied the law of exponents for power of a power mentioned in a', in the next stage we applied the law of exponents for multiplication of terms with identical bases mentioned in b', then we simplified the resulting expression.

Let's summarize the solution steps:

943813=(32)43831=38+(8)+(1)=3881=31 9^4\cdot3^{-8}\cdot\frac{1}{3}=(3^2)^4\cdot3^{-8}\cdot3^{-1} =3^{8+(-8)+(-1)}=3^{8-8-1}=3^{-1}

Therefore the correct answer is answer b'.

3

Final Answer

31 3^{-1}

Key Points to Remember

Essential concepts to master this topic
  • Base Conversion: Express all terms using the same base for simplification
  • Technique: Convert 94 9^4 to (32)4=38 (3^2)^4 = 3^8 using power rules
  • Check: Verify 31=13 3^{-1} = \frac{1}{3} matches the simplified expression ✓

Common Mistakes

Avoid these frequent errors
  • Working with different bases throughout the problem
    Don't leave 9 as 9 while working with powers of 3 = mixed bases make combining impossible! This prevents you from using exponent rules to simplify. Always convert everything to the same base first, then apply exponent laws.

Practice Quiz

Test your knowledge with interactive questions

\( 112^0=\text{?} \)

FAQ

Everything you need to know about this question

Why do I need to convert 9 to a power of 3?

+

Converting to the same base lets you use exponent rules! Since 9=32 9 = 3^2 , you can rewrite 94 9^4 as (32)4 (3^2)^4 and then combine all the 3's together.

How do I handle the fraction 1/3 in this problem?

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Remember that 13=31 \frac{1}{3} = 3^{-1} ! This negative exponent rule lets you convert fractions to exponential form so everything has the same base.

What's the difference between 3^{-1} and (1/3)^{-1}?

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31=13 3^{-1} = \frac{1}{3} , but (13)1=3 (\frac{1}{3})^{-1} = 3 ! The negative exponent flips the fraction, so be careful about which form you're working with.

Can I just multiply the exponents when I see (3^2)^4?

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Yes! Use the power of a power rule: (am)n=amn (a^m)^n = a^{mn} . So (32)4=32×4=38 (3^2)^4 = 3^{2 \times 4} = 3^8 .

How do I add exponents when multiplying terms with the same base?

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When multiplying terms with the same base, add the exponents: aman=am+n a^m \cdot a^n = a^{m+n} . So 383831=38+(8)+(1)=31 3^8 \cdot 3^{-8} \cdot 3^{-1} = 3^{8+(-8)+(-1)} = 3^{-1} .

Why is the final answer 3^{-1} instead of 1/3?

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Both forms are correct! 31 3^{-1} and 13 \frac{1}{3} represent the same value. The question asks for the exact form, and exponential notation often shows the work more clearly.

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