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Question

The value of the expression $\frac{1}{1+\log_u vw} + \frac{1}{1+\log_v wu} + \frac{1}{1+\log_w uv}$ is

The correct answer is
1

Simplifying the Logarithmic Expression

The problem asks for the value of the expression:

$ E = \frac{1}{1+\log_u vw} + \frac{1}{1+\log_v wu} + \frac{1}{1+\log_w uv} $

We can simplify each term using logarithm properties. Recall that $1 = \log_b b$ for any base $b$. Let's rewrite the denominators:

  • Term 1 Denominator: $1+\log_u vw = \log_u u + \log_u vw = \log_u (u \cdot vw) = \log_u (uvw)$
  • Term 2 Denominator: $1+\log_v wu = \log_v v + \log_v wu = \log_v (v \cdot wu) = \log_v (uvw)$
  • Term 3 Denominator: $1+\log_w uv = \log_w w + \log_w uv = \log_w (w \cdot uv) = \log_w (uvw)$

Now, substitute these back into the expression:

$ E = \frac{1}{\log_u (uvw)} + \frac{1}{\log_v (uvw)} + \frac{1}{\log_w (uvw)} $

Applying Change of Base Property

Using the logarithm property $\frac{1}{\log_a b} = \log_b a$, we can rewrite the expression:

$ E = \log_{uvw} u + \log_{uvw} v + \log_{uvw} w $

Combining Logarithms and Final Value

Using the logarithm property $\log_b x + \log_b y + \log_b z = \log_b (xyz)$, we combine the terms:

$ E = \log_{uvw} (u \cdot v \cdot w) $

$ E = \log_{uvw} (uvw) $

Finally, using the property $\log_b b = 1$:

$ E = 1 $

Therefore, the value of the expression is 1.

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Important Questions from Logarithms

  1. Real numbers $y$, $p$, and $n$ (all greater than 1) satisfy
    $$(\log_{p^{1/n}} y)(\log_{y^{1/n}} p) = 16,$$
    where the logarithms are taken to the bases $p^{1/n}$ and $y^{1/n}$.
    The value of $n$ is ________
  2. Consider two distinct positive real numbers $m, n$, with $m > n$.

    Let $x = n^{\log_{10}(m)}$ and $y = m^{\log_{10}(n)}$. The relation between $x$ and $y$ is _______.

  3. If $\log_x (5/7) = -1/3$, then the value of $x$ is
  4. A value of x that satisfies the equation $ \log x + \log (x - 7) = \log (x + 11) + \log 2 $ is
  5. For a real number $x > 1$, 
    $\frac{1}{\log_2 x} + \frac{1}{\log_3 x} + \frac{1}{\log_4 x} = 1$ 
    The value of $x$ is

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