Find the Missing Exponent: Solving 32 = (1/2)^x

Exponential Equations with Negative Exponents

32=(12)? 32=(\frac{1}{2})^?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Insert the missing exponent
00:03 Let's break down 32 to 2 to the power of 5
00:09 In order to eliminate a negative exponent
00:13 We'll flip the numerator and denominator and the exponent will become positive
00:18 Apply this formula to our exercise
00:28 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

32=(12)? 32=(\frac{1}{2})^?

2

Step-by-step solution

To solve this problem, let's follow these steps:

  • Step 1: Recognize that 32 can be expressed as a power of 2.
  • Step 2: Use negative exponents to equate (12)x \left(\frac{1}{2}\right)^x to this power of 2.
  • Step 3: Solve for the unknown exponent x x .

Now, let's work through each step:
Step 1: The number 32 can be expressed as a power of 2. Specifically, 32=25 32 = 2^5 .
Step 2: The expression (12)x \left(\frac{1}{2}\right)^x is equivalent to (21)x=2x \left(2^{-1}\right)^x = 2^{-x} . To find x x , equate: 25=2x 2^5 = 2^{-x} .
Step 3: Since the bases are equal, the exponents must be equal. Therefore, we have 5=x 5 = -x . Solving for x x , we multiply both sides by -1 and get x=5 x = -5 .

Therefore, the solution to the problem is x=5 x = -5 .

3

Final Answer

5 -5

Key Points to Remember

Essential concepts to master this topic
  • Rule: Convert fractions to negative exponents: (12)x=2x \left(\frac{1}{2}\right)^x = 2^{-x}
  • Technique: Express both sides as powers of same base: 32=25 32 = 2^5 and 2x 2^{-x}
  • Check: Verify: (12)5=25=32 \left(\frac{1}{2}\right)^{-5} = 2^5 = 32

Common Mistakes

Avoid these frequent errors
  • Making the exponent positive instead of negative
    Don't think (12)5=32 \left(\frac{1}{2}\right)^5 = 32 = 132 \frac{1}{32} ! This gives the reciprocal of what you need. Always remember that (1a)x=ax \left(\frac{1}{a}\right)^x = a^{-x} , so negative exponents flip the fraction.

Practice Quiz

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\( (2^3)^6 = \)

FAQ

Everything you need to know about this question

Why is the answer negative when we're looking for a positive result?

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The negative exponent is what makes (12)5 \left(\frac{1}{2}\right)^{-5} equal to a number greater than 1! When you have a negative exponent with a fraction, it flips the fraction and makes the exponent positive.

How do I remember that 32 equals 2 to what power?

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Start with powers of 2: 21=2,22=4,23=8,24=16,25=32 2^1=2, 2^2=4, 2^3=8, 2^4=16, 2^5=32 . Practice these basic powers - they come up frequently in exponential problems!

What if I can't see the pattern with powers of 2?

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Try working backwards! Since (12)x \left(\frac{1}{2}\right)^x means dividing by 2 repeatedly, ask yourself: How many times do I multiply by 2 to get from 1 to 32? That gives you the magnitude of your exponent.

Can I solve this using logarithms instead?

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Yes! You can use log1/2(32)=x \log_{1/2}(32) = x , but converting to the same base method is often simpler and doesn't require a calculator.

Why does a negative exponent make the answer bigger?

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With fractions, negative exponents flip the fraction! So (12)5=(21)5=25=32 \left(\frac{1}{2}\right)^{-5} = \left(\frac{2}{1}\right)^5 = 2^5 = 32 . The negative sign transforms the fraction into its reciprocal.

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