Solve: [(1/7)^-1]^4 Using Laws of Negative Exponents

Power Rules with Nested Exponents

[(17)1]4= [(\frac{1}{7})^{-1}]^4=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simply
00:06 We'll use the formula for power of power
00:10 Any number (A) raised to power (N) raised to power (M)
00:13 equals the same number (A) raised to the power of the sum of exponents (M+N)
00:16 We'll use this formula in our exercise
00:21 We'll multiply between the powers and calculate
00:29 Now we'll use the formula for negative exponent
00:32 When we have a negative exponent (-M) on any fraction (A/B)
00:36 We get the reciprocal number (B/A) raised to the positive exponent (M)
00:46 We'll use this formula in our exercise
00:50 We'll substitute the reciprocal number and the opposite exponent
00:53 And this is the solution to the question
01:03 New Chapter

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

[(17)1]4= [(\frac{1}{7})^{-1}]^4=

2

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

3

Final Answer

74 7^4

Key Points to Remember

Essential concepts to master this topic
  • Negative Exponent Rule: an=1an a^{-n} = \frac{1}{a^n} flips base to reciprocal
  • Power of Power Rule: (am)n=amn (a^m)^n = a^{m \cdot n} so (71)1=71 (7^{-1})^{-1} = 7^1
  • Check Final Result: [(17)1]4=74=2401 [( \frac{1}{7})^{-1}]^4 = 7^4 = 2401

Common Mistakes

Avoid these frequent errors
  • Adding exponents instead of multiplying them
    Don't add exponents like (-1) + (-1) + 4 = 2 giving 72 7^2 ! Power rules require multiplication, not addition. Always multiply exponents: (-1) × (-1) × 4 = 4 giving 74 7^4 .

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why does (17)1 (\frac{1}{7})^{-1} equal 7?

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The negative exponent rule says a1=1a a^{-1} = \frac{1}{a} . So (17)1=117=7 (\frac{1}{7})^{-1} = \frac{1}{\frac{1}{7}} = 7 . Think of it as flipping the fraction!

How do I handle multiple layers of exponents?

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Work from the innermost parentheses outward. First simplify (17)1=7 (\frac{1}{7})^{-1} = 7 , then apply the outer exponent: 74 7^4 .

When do I multiply exponents vs. add them?

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Multiply when you have a power raised to another power: (am)n=amn (a^m)^n = a^{m \cdot n} . Add when multiplying same bases: aman=am+n a^m \cdot a^n = a^{m+n} .

What if I get confused with all the negative signs?

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Take it step by step! Write each transformation clearly: 17=71 \frac{1}{7} = 7^{-1} , then (71)1=7(1)×(1)=71 (7^{-1})^{-1} = 7^{(-1) \times (-1)} = 7^1 , finally (71)4=74 (7^1)^4 = 7^4 .

How can I check if 74 7^4 is really the answer?

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Calculate both sides! 74=2401 7^4 = 2401 and the original expression [(17)1]4=74=2401 [(\frac{1}{7})^{-1}]^4 = 7^4 = 2401 . When they match, you're correct!

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