Answer
a) $2$
b) $\log_3(\dfrac{xy^4}{9})$
Work Step by Step
a) Since, $\log_39=\log _3(3)^3=2$
b) From part (a), we have
$\log_3 x+4\log_3 y-2=\log_3x+4\log_3 y-\log_39$
or, $\log_3 x+4\log_3 y-2=\log_3x+\log_3 y^4-\log_39$
or, $\log_3 x+4\log_3 y-2=\log_3(xy^4)-\log_39$
or, $\log_3 x+4\log_3 y-2=\log_3(\dfrac{xy^4}{9})$
Hence, a) $2$ b) $\log_3(\dfrac{xy^4}{9})$
