Use the properties of logarithms to find the exact values of
Use the properties of logarithms to find the exact values of the expressions. Do not use a calculator.
Solution
a) 10^(log30 -log5)
Use the log property : logA -logB = log(A/B)
So, 10^(log30/5 ) = 10^(log6)
Let y = 10^(log6) ; log y = log[10^(log6)]
logy = log6*log10
we know log10 = 1
SO, logy = log6
Hence y = 6
So, 10^(log30 -log5) =6
b) [log3(30)]*[ log30(9) ]
Use the property : loga(b) = logb/loga
[log(30)/log3]*[log(9)/log(30) ]
-- log30 gets cancelled
log(9)/log(3)
= 2log(3)/log(3)
= 2
