Calculate the Fraction: Finding the Value of 1/2^9

Negative Exponents with Reciprocal Conversion

129=? \frac{1}{2^9}=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:03 Let's solve this problem together!
00:06 Remember, when A is raised to the power of negative N,
00:10 it equals 1 divided by A to the power of N.
00:14 Let's use this rule to answer the question.
00:18 If we have 1 divided by 2, it becomes 2.
00:22 And the exponent 9 becomes negative 9.
00:25 And that's how we find the solution!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

129=? \frac{1}{2^9}=\text{?}

2

Step-by-step solution

We use the power property for a negative exponent:

an=1an a^{-n}=\frac{1}{a^n} We apply it to the given expression:

129=29 \frac{1}{2^9}=2^{-9}

Therefore, the correct answer is option A.

3

Final Answer

29 2^{-9}

Key Points to Remember

Essential concepts to master this topic
  • Rule: an=1an a^{-n} = \frac{1}{a^n} converts negative exponents to positive
  • Technique: 129 \frac{1}{2^9} becomes 29 2^{-9} using reciprocal property
  • Check: Both 129 \frac{1}{2^9} and 29 2^{-9} equal 1512 \frac{1}{512}

Common Mistakes

Avoid these frequent errors
  • Confusing negative exponents with negative bases
    Don't write 129=29 \frac{1}{2^9} = -2^9 = negative number! This changes the sign incorrectly and gives completely wrong values. Always remember that an a^{-n} means reciprocal, not negative.

Practice Quiz

Test your knowledge with interactive questions

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

FAQ

Everything you need to know about this question

What's the difference between 29 2^{-9} and 29 -2^9 ?

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29 2^{-9} means reciprocal and equals 1512 \frac{1}{512} (positive). 29 -2^9 means negative and equals 512 -512 . The negative exponent creates a fraction, not a negative number!

Why does 129 \frac{1}{2^9} equal 29 2^{-9} ?

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This uses the negative exponent rule: an=1an a^{-n} = \frac{1}{a^n} . Since we have 129 \frac{1}{2^9} , we can write it as 29 2^{-9} by moving the base to the other side and flipping the exponent sign.

Is 29 2^{-9} the same as (2)9 (-2)^9 ?

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No! 29 2^{-9} means positive 2 raised to negative 9 = 1512 \frac{1}{512} . (2)9 (-2)^9 means negative 2 raised to positive 9 = 512 -512 . The placement of parentheses matters!

How do I calculate 29 2^9 quickly?

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Build up step by step: 21=2 2^1 = 2 , 22=4 2^2 = 4 , 23=8 2^3 = 8 , 24=16 2^4 = 16 , 25=32 2^5 = 32 , 26=64 2^6 = 64 , 27=128 2^7 = 128 , 28=256 2^8 = 256 , 29=512 2^9 = 512 . Each step doubles the previous result!

Can I leave my answer as a decimal instead?

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You could calculate 1512=0.001953125 \frac{1}{512} = 0.001953125 , but 29 2^{-9} is the most precise form. Unless specifically asked for a decimal, the exponential form is preferred in mathematics.

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