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dauerbach
Average Member

USA
13 Posts

Posted - 08/27/2007 :  20:17:06  Show Profile
My back to school review is in progress, and I am blocking.

For the function f(x) =x^2 - 4/(x + 3)^2

State the domain: Every real number except -3

Find the x intercept: Totally blocking

Find the y Intercept: +4/9, -4/9

Are the two I did correct? What is the x intercept?
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tkhunny
Advanced Member

USA
1001 Posts

Posted - 08/27/2007 :  22:59:33  Show Profile
y-intercept: x = 0 and solve for y. Where does the graph hit the y-axis?

0^2 - 4/(0+3)^2 = 0 - 4/3^2 = -4/9

x-intercept: y = 0 and solve for x. Where does the graph hit the x-axis?

0 = x^2 - 4/(x+3)^2 = (x + 2/(x+3))(x - 2/(x+3))

Can you find values that work?

Domain: Good.
No Range?
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dauerbach
Average Member

USA
13 Posts

Posted - 08/29/2007 :  08:57:28  Show Profile
Honestly, I am not sure. I got -4/9 and it just seemed it should be plus or minus. Obviously not.
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tkhunny
Advanced Member

USA
1001 Posts

Posted - 08/29/2007 :  10:17:23  Show Profile
quote:
Originally posted by dauerbach

Honestly, I am not sure. I got -4/9 and it just seemed it should be plus or minus. Obviously not.

It is a common error. consider the following...

x = 4 has only one solution. x = 4

x = -4 has only one solution. x = -4

x = 4 has two solutions. x = 2 and x = -2

How many solutions has:

x = 4 ?

How many solutions has:

x = -4 ?
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