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 September 20th, 2012, 06:41 PM #1 Newbie   Joined: Sep 2012 Posts: 15 Thanks: 0 How do I express the domain in 'Interval Notation'? Find domain for the function: f(x)= x+3/x^2-6x+8 The domain cannot be zero on the denominator so, once expanded it's: Domain: x (cannot equal) 4,2 How would I write that the domain is all real number except 4,2?
 September 20th, 2012, 07:01 PM #2 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,155 Thanks: 461 Math Focus: Calculus/ODEs Re: How do I express the domain in 'Interval Notation'? In interval notation, this would be: $$$-\infty,2$$\,\cup\,$$2,4$$\,\cup\,$$4,\infty$$$
September 20th, 2012, 07:06 PM   #3
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Re: How do I express the domain in 'Interval Notation'?

Quote:
 Originally Posted by MarkFL In interval notation, this would be: $$$-\infty,2$$\,\cup\,$$2,4$$\,\cup\,$$4,\infty$$$
Sorry the domain is: x cannot equal -4,2

Because once I expand it's (x-4)(x+2)=0
So the domain would be -4,2.

Do I just express it as:
(-infinity,-4)U(-4,2)U(2,infinity)
??

 September 20th, 2012, 07:21 PM #4 Senior Member     Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,155 Thanks: 461 Math Focus: Calculus/ODEs Re: How do I express the domain in 'Interval Notation'? You had it right the first time: $x^2-6x+8=(x-2)(x-4)=0$ $x=2,4$ These are the values we exclude from the domain.

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# express domain in interval notatoin

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