Saturday 8 February 2014

LOGARITHMS B21

Evaluate Log5(125 x 625).

Solution

= Log5(125 x 625)

= Log5125 +  Log5625          (applying the product rule)

= Log553 +  Log554             ( 125= 53 and 625=54 by prime factorization)

= 3Log55 +  4Log55       ( remember  Logaac = cLogaa )

= (3 x 1) +  (4 x 1)          ( remember  Logaa = 1 )

= 3 + 4

= 7

Hence Log3(125 x 625) = 7


TRY THIS...............


Evaluate Log5(15625 x 625).

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