Q98 / 160 · WBJEE 2011 · Mathematics
If \(\log _7 2=\lambda\), then the value of \(\log _{49}(28)\) is
- A\((2 \lambda+1)\)
- B\((2 \lambda+3)\)
- Correct answerC\(\frac{1}{2}(2 \lambda+1)\)
- D\(2(2 \lambda+1)\)
Solution
Hints: \(\log _{49} 28=\log _{72} 4 \times 7\)
\(=\frac{1}{2}\left[2 \log _7 2+\log _7 7\right]=\frac{1}{2}[2 \lambda+1]\)
Hence, the correct answer is option: 'C'.