If and , which of the following yields…

MATHEMATICS · Single correct · AP · AP Precalculus · Exponential and Logarithmic Functions · Exponential and Logarithmic Functions

Problem

\log_3(x) = p

and

\log_7(x) = q

, which of the following yields

\log_{21}(x)

? (a)

pq

(b)

\frac{1}{p+q}

(c)

\frac{1}{p^{-1}+q^{-1}}

(d)

\frac{pq}{p^{-1}+q^{-1}}