Bike Forums > Foo > Find f(-x)?
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 Foo Off-Topic chit chat with no general subject.

 07-13-08, 02:49 PM #1 phantomcow2 la vache fantôme Thread Starter     Join Date: Aug 2004 Location: NH Bikes: Posts: 6,266 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 1 Post(s) Find f(-x)? I am being prompted to find f(-x) of the following function: So plug in -x for x. (4*-x) + 1/(4*-x) -4x + 1/(-4x) Find a common denominator, which in this case is -4x. So, I multiplied the left term by (-4x)/(-4x) This gives me 16x^2 + 1/(-4x) Is that correct? I only have one attempt remaining in my web applet. __________________ C://dos C://dos.run run.dos.run
 07-13-08, 03:20 PM #2 apricissimus  L T X B O M P F A N S R     Join Date: Jun 2008 Location: Malden, MA Bikes: Bianchi Volpe, Bianchi San Jose, Redline 925 Posts: 2,334 Mentioned: 2 Post(s) Tagged: 0 Thread(s) Quoted: 1638 Post(s) The correct answer is (16x^2 + 1)/(-4x). You omitted the parentheses in the numerator, though I'm sure it was just an oversight.
 07-13-08, 04:43 PM #3 phantomcow2 la vache fantôme Thread Starter     Join Date: Aug 2004 Location: NH Bikes: Posts: 6,266 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 1 Post(s) Okay, well I did get that right. Now how about this: Find the domain. __________________ C://dos C://dos.run run.dos.run
 07-13-08, 04:47 PM #4 phantomcow2 la vache fantôme Thread Starter     Join Date: Aug 2004 Location: NH Bikes: Posts: 6,266 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 1 Post(s) I'm stumped. At first I thought the domain would be [3,INF]. The reason being that 3 is the minimum number which can be inputted into this function and still get a real number. THe reason being the sqrt(x-3) __________________ C://dos C://dos.run run.dos.run
 07-14-08, 07:56 AM #5 apricissimus  L T X B O M P F A N S R     Join Date: Jun 2008 Location: Malden, MA Bikes: Bianchi Volpe, Bianchi San Jose, Redline 925 Posts: 2,334 Mentioned: 2 Post(s) Tagged: 0 Thread(s) Quoted: 1638 Post(s) That is the correct answer. Does your applet thingy (or whatever it is) say it's wrong? (BTW, my creds: BA in math; am currently an editor of math textbooks)
 07-14-08, 07:57 AM #6 apricissimus  L T X B O M P F A N S R     Join Date: Jun 2008 Location: Malden, MA Bikes: Bianchi Volpe, Bianchi San Jose, Redline 925 Posts: 2,334 Mentioned: 2 Post(s) Tagged: 0 Thread(s) Quoted: 1638 Post(s) If you're typing in [3,INF], try typing [3,INF), since technically, an interval that does off to infinity is open on that end, not closed.