Saturday 25 April 2015

LOGARITHMS 18




If Logb343 – log 0.001 = 8; find b

Solution

Logb343 – log 0.001 = 6;            [0.001=10-3 ]

Logb343 – log 10-3 = 6      

Logb343 – (-3log 10) = 6

Logb343 + 3log 10 = 6   [remember log 10 = 1]

Logb343 + (3 x 1) = 6

Logb343 + 3 = 6

Logb343 = 6 - 3

Logb343 = 3     [Change it into exponential notation]

343 = b3

73 = b3      [ 243 = 73 by prime factorization]

73 = b3  [ bases are same on both sides, so they cancel out ]

b = 7


Hence b = 7    


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

If Loga64 – log 0.00001 = 11; find a


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