4. LOGARITHMIC FUNCTION MODELS
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We view the graphs of y = ln x and y = log x together.
All logarithmic graphs pass through the point (1, 0) and have the y-axis as a
vertical asymptote.
For x > 1, the smaller the base, the larger the values of the logarithm.
For x < 1, the smaller the base, the smaller (more negative) the values of the
logarithm.
When b > 1, logb x increases at a decreasing rate (concave down).
When 0 < b < 1, logb x decreases at an increasing rate (concave up), i.e., at a
rate that is less and less negative.