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logarithmic function
[logarithmic function|logarithmic function] is defined only when the input is positive.
Definition
logarithmic function is defined only when the input is positive. Its inverse is an exponential function.
Mechanism
To determine the domain of logarithmic function, the inequality x - 5 > 0 must be solved, resulting in x > 5. This follows from the definition requiring x > 0 for f(x) = log_a x.
Effects
The argument of logarithmic function must be positive, which determines where x + 2 x − 4 > 0.