back to *Trigonometry*
# Exponential Equation

- Question 5
- f(x) = 2
^{x}+ 3 is a function. If f(x) = 10, find x = ?

- Solution
- Given f(x) = 10, then 2
^{x}+ 3 = 10 => 2^{x}= 7 - Take log to both sides
- log2
^{x}= log 7 => x log2 = log 7 - x = log 7/log 2 = 0.8451/0.3010 = 2.8076

- Formula used:
- log
_{a}b^{x}= x log_{a}b