To solve the equation \( \log_2(3x + 1) \cdot \log_3 x = 2 \cdot \log_2(3x + 1) \), we can start by simplifying it step-by-step.
First, let's rewrite the equation for clarity:
\[ \log_2(3x + 1) \cdot \log_3 x - 2 \cdot \log_2(3x + 1) = 0 \]
Factoring out \(\log_2(3x + 1)\):
\[ \log_2(3x + 1) \left( \log_3 x - 2 \right) = 0 \]
This product equals zero if either one of the factors equals zero:
- \(\log_2(3x + 1) = 0\)
- \(\log_3 x - 2 = 0\)
For the first case:
\(\log_2(3x + 1) = 0\) implies:
\[ 3x + 1 = 2^0 \implies 3x + 1 = 1 \implies 3x = 0 \implies x = 0 \]
However, \(x = 0\) is not valid because logarithms are undefined for non-positive values.
For the second case:
\(\log_3 x - 2 = 0\) implies:
\[ \log_3 x = 2 \implies x = 3^2 \implies x = 9 \]
Conclusion:
The only potential solution to the equation is \(x = 9\).
To ensure that it is valid, let's check if it satisfies the original equation:
Calculating:
- \(3x + 1 = 3(9) + 1 = 27 + 1 = 28\)
- \(\log_2(28) \cdot \log_3(9) = \log_2(28) \cdot 2\) (since \(\log_3(9) = \log_3(3^2) = 2\))
- The right side is \(2 \cdot \log_2(28)\).
Both sides are equal. Thus, the solution is confirmed.
The solution is:
\[ \boxed{9} \]