WAEC 2023 · Paper 1 · Q45

Logarithms

If $\log_a 3 = m$ and $\log_a 5 = p$ , find $\log_a 75$ .

Worked solution (try it first)

Write 75 using 3 and 5: $75 = 3 \times 25 = 3 \times 5^2$ .
So $\log_a 75 = \log_a 3 + 2\log_a 5$ .
That is $m + 2p$ , option C.

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