## Derivative : solution for exercise 4.11 - Basic math level

### In mathematics, the logarithm of a number to a given base is the power or exponent to which the base must be raised in order to produce the number. For example, the logarithm of *81* to the base *3* is *4*, because *4* is the number of *3s* that must be multiplied together to get *81*: thus *3 × 3 × 3 × 3 = 81*. In the language of exponents: *3*^{4} = 81, so *log*_{3}(81) = 4.