Solve 7⁴ × 8³ × (1/7)⁴: Power and Reciprocal Multiplication

Power Rules with Reciprocal Simplification

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

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:09 Let's simplify the problem together.
00:15 If a fraction has an exponent, both the top and bottom numbers are raised to that power.
00:24 We'll use this rule for our exercise, so let's get started!
00:30 Now, let's reduce wherever we can.
00:38 Remember, one raised to any power is always one.
00:44 And there you go, that's the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

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

2

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

3

Final Answer

83 8^3

Key Points to Remember

Essential concepts to master this topic
  • Rule: (1a)n=1an (\frac{1}{a})^n = \frac{1}{a^n} converts reciprocals to fraction form
  • Technique: Cancel 74 7^4 with 174 \frac{1}{7^4} leaving only 83 8^3
  • Check: Verify 74×174=1 7^4 \times \frac{1}{7^4} = 1 and 1×83=512 1 \times 8^3 = 512

Common Mistakes

Avoid these frequent errors
  • Adding exponents instead of recognizing cancellation
    Don't add 4 + 3 + 4 = 11 thinking the answer is some power with exponent 11! This ignores that 74 7^4 and (17)4=174 (\frac{1}{7})^4 = \frac{1}{7^4} are reciprocals that multiply to 1. Always look for bases that can cancel first.

Practice Quiz

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\( (2^3)^6 = \)

FAQ

Everything you need to know about this question

Why does 74×(17)4 7^4 \times (\frac{1}{7})^4 equal 1?

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Because (17)4=174 (\frac{1}{7})^4 = \frac{1}{7^4} , so you get 74×174=7474=1 7^4 \times \frac{1}{7^4} = \frac{7^4}{7^4} = 1 . Any number divided by itself equals 1!

Can I calculate 74 7^4 and 83 8^3 separately first?

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You could, but it's unnecessary work! 74=2401 7^4 = 2401 and 83=512 8^3 = 512 , but since 74 7^4 cancels with 174 \frac{1}{7^4} , you just need 83=512 8^3 = 512 .

What if the bases were different, like 74×83×(16)4 7^4 \times 8^3 \times (\frac{1}{6})^4 ?

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Then nothing would cancel! You'd need to calculate each part separately: 74×83×164 7^4 \times 8^3 \times \frac{1}{6^4} . Cancellation only works when bases are the same.

How do I know when to look for cancellation?

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Always scan for matching bases with reciprocal relationships! If you see an a^n and (1a)n (\frac{1}{a})^n or 1an \frac{1}{a^n} , they will cancel to 1.

Why is 14 1^4 important in the solution?

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Because (17)4=1474 (\frac{1}{7})^4 = \frac{1^4}{7^4} , and any power of 1 equals 1. This helps show that after cancellation, we're left with 83×1=83 8^3 \times 1 = 8^3 .

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