1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Intercepts and graphs

  1. Feb 8, 2010 #1
    Alright lets says for example we were to sketch y=(x-2)(x-3). You would find x intercepts and you would write it as x-2=0 OR x-3=0, thus x=2 OR x=3. Why do we use the word OR when we use both of the intercepts to sketch the graph anyway? Why cannot we use AND instead.
     
  2. jcsd
  3. Feb 8, 2010 #2

    Mentallic

    User Avatar
    Homework Helper

    Re: Intercepts

    To find the x-intercepts, which is where y=0, when you have two variables multiplied together to equal zero, you only need one or the other to be 0.

    e.g. if you have ab=0, where a and b are not equal, then a can be 0 or b can be 0, but since a is not equal to b then you can't have a and b are 0.

    Same thing goes with that quadratic. (x-2)(x-3)=0 means that for some value x, the first factor (x-2) will equal zero while the second won't, and similarly for the second factor. This is why it is said x-2=0 OR x-3=0.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook