Question
If $2 \log x + 1 = 40$, find: $\log 5x$
✓
Answer
$2 \log x + 1 = 40$
$\Rightarrow 2\log x + \log10 = 40$
$\Rightarrow 2\log 10x = 40$
$\Rightarrow \log2 \times 5x = 20$
$\Rightarrow \log2 + \log5x = 20$
$\Rightarrow \log5x = 20 - \log2$
$\Rightarrow \log5x = 20 - 0.3010 ......($Since $\log2 = 0.3010)$
$\Rightarrow \log5x = 19.6989.$
$\Rightarrow 2\log x + \log10 = 40$
$\Rightarrow 2\log 10x = 40$
$\Rightarrow \log2 \times 5x = 20$
$\Rightarrow \log2 + \log5x = 20$
$\Rightarrow \log5x = 20 - \log2$
$\Rightarrow \log5x = 20 - 0.3010 ......($Since $\log2 = 0.3010)$
$\Rightarrow \log5x = 19.6989.$
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