2.Let us now solve a few problems applying the logarithm formulas and concepts learned so far.
1. Change the following exponential forms into logarithmic forms.
1. 23 = 8 2. 3√(64) = 4  3.; (√2)8 = 16
Solution:
1. we know that if
ax = n, then log a n = x
therefore, if
23 = 8, then log 2 8 = 3
2. 3√(64)
= (64)1/3 = 4
log 64 4 = 1/3
3. (√2)8 = 16
log √2 16 = 8
2. Change the following logarithmic forms into exponential forms:
1. log 4 16 = 2 2. log 6 36 = 2 3. log a 3√(x) = 1/y
Recall that if
log a x = n, then an = x
Solution1:
log 416 = 2, 42 = 16
Solution 2:
log 6 36 = 2, 62 = 36
Solution 3:
log a 3√(x) = 1/y ,
a1/y = 3√(x)
a1/y = x1/3
2. Find log 2 (log 3 81) = log 3 X
Solution:
Let log 3 81 = n,
then 3n = 81,
3 n = 34 ,
n = 4
so, in the given question,
log 2 (log 381) reduces to log 2 4.
Now the question is
log 2 4 = log 3 X…………………..(2)
again, let
log 2 4 = n,
then 2n = 4 = 22, so n = 2
writing n = 2 in (2), we get
2 = log 3 X
So, 32 = X
X = 9
Now, we will learn simple laws of logarithms to solve above type of problems easily and in far fewer steps in the following pages.