Solve (4·7)^9 + 2^7/2^4 + (8^2)^5: Complex Exponent Calculation

Exponent Rules with Multiple Operations

(47)9+2724+(82)5= (4\cdot7)^9+\frac{2^7}{2^4}+(8^2)^5=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve the following problem
00:03 When there's a power over a product of numbers, all terms are raised to that power
00:08 When dividing powers with equal bases
00:13 The power of the result equals the difference of the powers
00:19 Let's use this formula in our exercise
00:23 When there's a power of a power, the resulting power is the product of the powers
00:29 Let's use this formula in our exercise
00:33 Let's calculate all the powers
00:43 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

(47)9+2724+(82)5= (4\cdot7)^9+\frac{2^7}{2^4}+(8^2)^5=

2

Step-by-step solution

In order to solve the problem we must use two power laws, as shown below:

A. Power property for terms with identical bases:

aman=amn \frac{a^m}{a^n}=a^{m-n} B. Power property for an exponent raised to another exponent:

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

We will apply these two power laws to the problem in two steps:

Let's start by applying the power law specified in A to the second term from the left in the given problem:

2724=274=23 \frac{2^7}{2^4}=2^{7-4}=2^3 In the first step we apply the power law specified in A and then proceed to simplify the resulting expression,

We then advance to the next step and apply the power law specified in B to the third term from the left in the given problem :

(82)5=825=810 (8^2)^5=8^{2\cdot5}=8^{10} In the first stage we apply the power law specified in B and then proceed to simplify the resulting expression,

Let's summarize the two steps listed above to solve the general problem:

(47)9+2724+(82)5=(47)9+23+810 (4\cdot7)^9+\frac{2^7}{2^4}+(8^2)^5= (4\cdot7)^9+2^3+8^{10} In the final step, we calculate the result of multiplying the terms within the parentheses in the first term from the left:

(47)9+23+810=289+23+810 (4\cdot7)^9+2^3+8^{10}=28^9+2^3+8^{10} Therefore, the correct answer is option c.

3

Final Answer

289+23+810 28^9+2^3+8^{10}

Key Points to Remember

Essential concepts to master this topic
  • Division Rule: aman=amn \frac{a^m}{a^n} = a^{m-n} when bases are identical
  • Power Rule: (am)n=amn (a^m)^n = a^{m \cdot n} like (82)5=810 (8^2)^5 = 8^{10}
  • Verification: Check each step: 27/24=23=8 2^7/2^4 = 2^3 = 8 and (82)5=810 (8^2)^5 = 8^{10}

Common Mistakes

Avoid these frequent errors
  • Adding exponents when dividing powers
    Don't add exponents like 2724=211 \frac{2^7}{2^4} = 2^{11} = wrong answer! This confuses multiplication rules with division rules. Always subtract exponents when dividing: 2724=274=23 \frac{2^7}{2^4} = 2^{7-4} = 2^3 .

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

When do I add exponents versus subtract them?

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Add exponents when multiplying: aman=am+n a^m \cdot a^n = a^{m+n}

Subtract exponents when dividing: aman=amn \frac{a^m}{a^n} = a^{m-n}

Remember: multiplication adds, division subtracts!

What's the difference between (82)5 (8^2)^5 and 8285 8^2 \cdot 8^5 ?

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(82)5=82×5=810 (8^2)^5 = 8^{2 \times 5} = 8^{10} (power raised to a power = multiply exponents)

8285=82+5=87 8^2 \cdot 8^5 = 8^{2+5} = 8^7 (same base multiplication = add exponents)

These give completely different results!

Why doesn't (47)9 (4 \cdot 7)^9 become 4979 4^9 \cdot 7^9 ?

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Actually, it could become 4979 4^9 \cdot 7^9 using the rule (ab)n=anbn (ab)^n = a^n b^n , but that makes the problem much harder!

It's easier to multiply inside first: (47)9=289 (4 \cdot 7)^9 = 28^9

Can I use a calculator for these large exponents?

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For this problem, you don't need to calculate the actual values! The question asks for the simplified form.

289+23+810 28^9 + 2^3 + 8^{10} is the final answer, not the huge number you'd get from calculating each term.

How do I remember which exponent rule to use?

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  • Same base, multiplying? Add exponents: aman=am+n a^m \cdot a^n = a^{m+n}
  • Same base, dividing? Subtract exponents: aman=amn \frac{a^m}{a^n} = a^{m-n}
  • Power raised to power? Multiply exponents: (am)n=amn (a^m)^n = a^{m \cdot n}

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