Solution 3.3:6c
From Förberedande kurs i matematik 1
Before we even start thinking about transforming
lga
a
b
=lga+lgb
to simplify the expression
118
log23
=log3118+log3log23
With help of the relation
and taking the natural logarithm , we can express
The two terms log3 118 and log3 log2 3 can therefore be written as
ln2ln3
where we can simplify the last expression further with the logarithm law, log a/b = log a – log b, and then transform
ln2ln3
=log3ln3−log3ln2=ln3lnln3−ln3ln2
In all, we thus obtain
Input into the calculator gives
4
762
NOTE: the button sequence on a calculator will be:
1
1
8
LN
3
LN
+
3
LN
LN
3
LN
−
2
LN
LN
3
LN
=