Expand the Expression: Calculate 8^4 Step by Step

Exponent Decomposition with Product Rule

Expand the following equation:

84= 8^4=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Identify which expressions are equal
00:03 According to the laws of exponents, the multiplication of powers with an equal base (A)
00:07 equals the same base raised to the sum of the exponents (N+M)
00:11 We will apply this formula to our exercise in order to simplify it
00:15 We can observe that this expression equals the original expression
00:20 And this expression also equals the original expression
00:27 All the expressions are equal to the original
00:30 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Expand the following equation:

84= 8^4=

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Understand the given information, which is the expression 84 8^4 .
  • Step 2: Check each choice to see if it is a valid decomposition of 84 8^4 .
  • Step 3: Validate each decomposition by applying the formula am×an=am+n a^m \times a^n = a^{m+n} .

Now, let's work through each step:
Step 1: The given expression is 84 8^4 . We need to expand it using the properties of exponents.
Step 2: Check each choice:
- Choice 1: 81×83 8^1 \times 8^3 . According to the law am×an=am+n a^m \times a^n = a^{m+n} , this gives 81+3=84 8^{1+3} = 8^4 . Correct.
- Choice 2: 82×82 8^2 \times 8^2 . Similarly, 82+2=84 8^{2+2} = 8^4 . Correct.
- Choice 3: 83×81 8^3 \times 8^1 . This gives 83+1=84 8^{3+1} = 8^4 . Correct.
Step 3: All choices decompose 84 8^4 correctly into powers of 8 that multiply back to the original value, confirming their validity.

Therefore, the solution to the problem is all answers are correct.

3

Final Answer

All answers are correct

Key Points to Remember

Essential concepts to master this topic
  • Product Rule: When multiplying same bases, add exponents: am×an=am+n a^m \times a^n = a^{m+n}
  • Technique: Split 84 8^4 into pairs like 82×82=82+2=84 8^2 \times 8^2 = 8^{2+2} = 8^4
  • Check: Add all exponents to verify they equal the original: 1+3=4, 2+2=4, 3+1=4 ✓

Common Mistakes

Avoid these frequent errors
  • Multiplying bases instead of adding exponents
    Don't write 82×82=164 8^2 \times 8^2 = 16^4 by multiplying the bases! This creates a completely different expression with wrong value. Always keep the same base and add the exponents: 82×82=82+2=84 8^2 \times 8^2 = 8^{2+2} = 8^4 .

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why can I break apart 84 8^4 in so many different ways?

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The product rule for exponents works in reverse! Since am×an=am+n a^m \times a^n = a^{m+n} , you can split any exponent into parts that add up to the original. As long as the exponents add to 4, like 1+3, 2+2, or 3+1, they're all correct!

Do the bases always have to be the same number?

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Yes! The product rule only works when the bases are identical. You cannot combine 82×72 8^2 \times 7^2 using this rule because 8 and 7 are different bases.

What if I want to split 84 8^4 into three parts instead of two?

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That works perfectly! You could write 84=81×81×82 8^4 = 8^1 \times 8^1 \times 8^2 or 84=81×81×81×81 8^4 = 8^1 \times 8^1 \times 8^1 \times 8^1 . Just make sure all the exponents add up to 4!

How do I check if my decomposition is correct?

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Use two methods: 1) Add the exponents to see if they equal the original (like 2+2=4), and 2) Calculate both expressions to verify they give the same numerical value.

Is there a 'best' way to decompose an exponent?

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Not really! All valid decompositions are mathematically correct. However, equal splits like 82×82 8^2 \times 8^2 are often most useful for further calculations because they create identical factors.

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