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Question

For positive integers $p$ and $q$, with $\frac{p}{q} \neq 1$, $(\frac{p}{q})^{\frac{p}{q}} = p^{(\frac{p}{q}-1)}$. Then,

The correct answer is
$q^p = p^q$

Algebraic Simplification: Finding the Relation Between p and q

We are given the equation $(\frac{p}{q})^{\frac{p}{q}} = p^{(\frac{p}{q}-1)}$ where $p$ and $q$ are positive integers and $\frac{p}{q} \neq 1$. We need to find the relationship between $p$ and $q$. Let's simplify the equation using logarithms.

Step 1: Apply Natural Logarithm

Take the natural logarithm (ln) of both sides of the equation:

$\ln\left((\frac{p}{q})^{\frac{p}{q}}\right) = \ln\left(p^{(\frac{p}{q}-1)}\right)$

Step 2: Use Logarithm Properties

Apply the power rule of logarithms, $\ln(a^b) = b \ln(a)$, to both sides:

$\frac{p}{q} \ln(\frac{p}{q}) = (\frac{p}{q}-1) \ln(p)$

Now, apply the quotient rule of logarithms, $\ln(\frac{a}{b}) = \ln(a) - \ln(b)$, to the left side:

$\frac{p}{q} (\ln(p) - \ln(q)) = (\frac{p}{q}-1) \ln(p)$

Step 3: Simplify the Equation

Distribute the terms:

$\frac{p}{q} \ln(p) - \frac{p}{q} \ln(q) = \frac{p}{q} \ln(p) - \ln(p)$

Subtract $\frac{p}{q} \ln(p)$ from both sides:

$- \frac{p}{q} \ln(q) = - \ln(p)$

Multiply both sides by -1:

$\frac{p}{q} \ln(q) = \ln(p)$

Step 4: Rearrange and Apply Logarithm Properties

Multiply both sides by $q$:

$p \ln(q) = q \ln(p)$

Use the power rule of logarithms ($b \ln(a) = \ln(a^b)$) in reverse:

$\ln(q^p) = \ln(p^q)$

Step 5: Determine the Final Relation

Since the natural logarithm function is one-to-one, if $\ln(x) = \ln(y)$, then $x=y$. Therefore:

$q^p = p^q$

This relationship matches Option 1.

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Important Questions from Powers and Exponents

  1. The digit in the unit's place of the product $3^{999} \times 7^{1000}$ is __________.
  2. Which one of the following numbers is exactly divisible by $(11^{13} +1)$?
  3. Consider the following functions for non-zero positive integers, $p$ and $q$.


    Which one of the following options is correct based on the above?

     

  4. What is the value of x when $81 \times \left(\frac{16}{25}\right)^{x+2} \div \left(\frac{3}{5}\right)^{2x+4} = 144$?
  5. What is the value of $\left(\frac{3^{81}}{27^4}\right)^{1/3}$?
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