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Rational Functions - Intercepts

These are easy!

Y-INTERCEPTS:  Where the graph crosses the y-axis

OK, think about it...  When you are on the y-axis, what is your
x value?

Graph of the point ( 0 , 2 )The x value is 0.

So, find the y-intercept...
Set x = 0!

That's the same as finding f(0).

Check it out:

f( x ) = ( x^2 - x - 6 ) / ( x^2 - 1 )
 
 
f( 0 ) = ( ( 0 )^2 - 0 - 6 ) / ( ( 0 )^2 - 1 ) = 6
 
 

So, the y-intercept for this guy is the point

( 0 , 6 )

 

TRY IT:

Find the y-intercept of

f( x ) = ( x - 3 ) / ( x^2 - 3x - 10 )