Diketahui ?log 3 = a dan “log 5 = b. Nilai log 40 adalah ..​

Jawaban:

log 3 = a

log 5 = b

maka:

log 40 = log 2³x5

= 3xlog 2 + log 5

= 3 x log (10/5) + log 5

= 3 x (log 10 – log 5) + log 5

= 3 x (1-b) + b

= 3 x 1 – b + b

= 3