Simplify the Expression: Converting 1/(20²) to Its Final Form

Negative Exponents with Reciprocal Conversion

Insert the corresponding expression:

1202= \frac{1}{20^2}=

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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 According to the exponent laws, a number raised to the power of (-N)
00:06 equals the reciprocal number raised to the opposite power (N)
00:10 We'll apply this formula to our exercise
00:13 We'll convert to the reciprocal number, and raise it to the opposite power (times(-1))
00:17 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Insert the corresponding expression:

1202= \frac{1}{20^2}=

2

Step-by-step solution

To solve this problem, we will use the properties of exponents. Specifically, we will convert the expression 1202 \frac{1}{20^2} into a form that uses a negative exponent. The general relationship is that 1an=an \frac{1}{a^n} = a^{-n} .

Applying this rule to the given expression:

  • Step 1: Identify the current form, which is 1202 \frac{1}{20^2} .
  • Step 2: Apply the negative exponent rule: 1202=202 \frac{1}{20^2} = 20^{-2} .
  • Step 3: This expression, 202 20^{-2} , represents 1202 \frac{1}{20^2} using a negative exponent.

Therefore, the expression 1202 \frac{1}{20^2} can be expressed as 202 20^{-2} , which aligns with choice 1.

3

Final Answer

202 20^{-2}

Key Points to Remember

Essential concepts to master this topic
  • Rule: 1an=an \frac{1}{a^n} = a^{-n} converts fractions to negative exponents
  • Technique: Move base from denominator to numerator and flip exponent sign
  • Check: Verify 202=1202=1400 20^{-2} = \frac{1}{20^2} = \frac{1}{400}

Common Mistakes

Avoid these frequent errors
  • Adding negative signs incorrectly
    Don't write 202 -20^{-2} when converting 1202 \frac{1}{20^2} = negative answer when original is positive! The negative sign applies to the exponent only, not the base. Always keep the base positive and make only the exponent negative.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

Why does the exponent become negative when I move it?

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Think of it as "paying a penalty" for moving from the denominator to the numerator. The negative exponent tells you the number is really in the denominator: 202 20^{-2} means "20 squared, but in the bottom of a fraction."

Is 202 20^{-2} the same as 202 -20^2 ?

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No! 202=1400 20^{-2} = \frac{1}{400} (positive), but 202=400 -20^2 = -400 (negative). The negative sign's position matters: negative exponent vs negative base.

Can I calculate the decimal value instead?

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You could calculate 1202=1400=0.0025 \frac{1}{20^2} = \frac{1}{400} = 0.0025 , but the question asks for the equivalent expression, not the decimal value. Stick with 202 20^{-2} .

What if the base was negative, like 1(5)3 \frac{1}{(-5)^3} ?

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Same rule applies! 1(5)3=(5)3 \frac{1}{(-5)^3} = (-5)^{-3} . The parentheses stay with the base, and only the exponent becomes negative. Keep the entire base the same.

How do I remember this rule?

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Think: "Flip the fraction, flip the sign" - when you move a power from bottom to top (or vice versa), the exponent sign flips too. It's like the exponent's way of remembering where it came from!

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