Saturday, November 15, 2008

Natural Logarithmic Function and Solving Logarithmic Functions and Exponential Functions

Image:Lnex.svg
Here is a graph (courtesy of wikipedia.org) that illustrates the graph of ln(x) (the green line).  As can be seen from the graph, as you move to the right from the origin, the graph above the y=0 line starts to increase and move upward.  At the same time, moving from right to left, the graph approaches a vertical asymptote at x=0.

Solving exponential equations -

 For this part, we're going to look at the equation tex2html_wrap_inline119 .

The first thing to do is to tak the Ln of both sides.

displaymath121

That leaves us with the following equation.

displaymath123

The Ln(e) cancels out, and we are left with -

displaymath127

which can easily be solved on a calculator.



Solving a logarithmic equation such as -

displaymath43



Move the 4 to the other side of the equation.

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Make the logarithmic function into an exponential function by making it 3^6

displaymath55

Divide each side of the equation by seven.

displaymath57

And there you have it.

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