To determine which logarithmic expression is undefined, we need to consider the properties of logarithms:
- The logarithm of a positive number is defined.
- The logarithm of zero or a negative number is undefined.
Now let's analyze each of the given expressions:
- log₂(6.25): This is defined because 6.25 is positive.
- log₃(27): This is defined because 27 is positive.
- log₃(-9): This is undefined because -9 is negative.
- log₀(256): This is undefined because 0 is not a valid base for logarithm.
The logarithmic expression that is undefined is log₃(-9).