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Here's a special exponential that I haven't told you about yet:

y = 10^( x )

He's got a special inverse too...

y = log to the base 10( x )

This log turns up so much (biology, chemistry, geology, sound engineering and more), it's  called "the common log."  It even has its own button on your calculator!

LOG

See it?  Notice that they leave the base, 10, off?

It's because this is the most commonly used log, so the 10 is just assumed.  From now on, when you see

y = log( x ), it's reallyy = log to the base 10( x ).

(Just like you leave the 2 off the square root...)

root^( 2 )( x ) = square root( x )

Let's review the graph of y = 10^( x ):

 

x: -1 , 0 , 1 ... y: 1 / 10 , 1 , 10graph of y = 10^( x )

 

Now, you can graph his inverse, y = log x:

* Remember to switch the x's and y's!