Tuesday, 21 April 2015

LOGARITHMS 15


If Logb8 – log 0.00001 = 8; find b

Solution

Logb8 – log 0.001 = 6;            [0.00001=10-5 ]

Logb8 – log 10-3 = 6      

Logb8 – (-3log 10) = 6

Logb8 + 3log 10 = 6   [remember log 10 = 1]

Logb8 + (3 x 1) = 6

Logb8 + 3 = 6

Logb8 = 6 - 3

Logb8 = 3     [Change it into exponential notation]

8 = b3

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

b = 2


Hence b = 2    


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


If Loga729 – log 0.00001 = 11; find a

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