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Chapter 5. Logarithmic, Exponential, and Other Transcendental Functions. A logarithm is an exponent!. For x 0 and 0 a 1, y = log a x if and only if x = a y . The function given by f ( x ) = log a x i s called the logarithmic function with base a.
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Chapter 5 Logarithmic, Exponential, and Other Transcendental Functions
A logarithm is an exponent! For x 0 and 0 a 1, y = loga x if and only if x = ay. The function given by f(x) = loga x is called the logarithmic function with base a. Every logarithmic equation has an equivalent exponential form: y= loga x is equivalent to x =ay A logarithmic function is the inverse function of an exponential function. Exponential function: y = ax Logarithmic function: y = logax is equivalent to x = ay
y (x 0, e 2.718281) x 5 –5 y = ln x is equivalent to ey = x y = ln x The function defined by f(x) = logex = ln x is called the natural logarithm function. In Calculus, we work almost exclusively with natural logarithms!
Natural Log Passes through (1,0) and (e,1). You can’t take the log of zero or a negative. (Same graph 1 unit right)
Properties of Natural Log: Expand: Write as a single log:
Properties of Natural Log: Expand: Write as a single log:
Derivative of Logarithmic Functions The derivative is Notice that the derivative of expressions such as ln|f(x)| has no logarithm in the answer. Example: Solution:
Example Product Rule
4. Show that is a solution to the statement .
4. Show that is a solution to the statement .
Find the equation of the line tangent to: at (1, 3) At (1, 3) the slope of the tangent is 2
Find the equation of the tangent line to the graph of the function at the point (1, 6).