Logarithms同Growth or Decay

Please show all clear steps, thank you.

Ex1. If (log a) base x = 2 and (log b) base x = 5, evaluate the following.
a) log (third root of ab) base x

Ex2. Solve the following equations.
a) log[(x^2)-3x+6] = 1

Ex3. The percent of carbon-14 of a dead plant or animal can be determined by the following equation. A = Ae^(-0.000124t) base o
a) Estimate the age of a bone if 30% of the original amount of carbon-14 was still present.

Ex4. If the world population is now 4.5 billion and if it has been growing continuously at an average rate 2.3% per year. Equation P=4.5e^(1x0.023)
a) How long will it take for the population to grow to 5 billion?

I need help badly, thank you.