ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: lisafaustina on October 08, 2010, 08:18:07 pm

Title: inequalities
Post by: lisafaustina on October 08, 2010, 08:18:07 pm
when do we swap the inequality sign?
Title: Re: inequalities
Post by: ilovecake on October 08, 2010, 08:20:16 pm
When you multiply or divide by a negative number I believe.
Title: Re: inequalities
Post by: 8039 on October 08, 2010, 08:37:54 pm
Sometimes when finding solutions for quadratic inequalities I think you have to graph the parabola and through observation decide which which on of your values is greater or less than then intersection point.
Title: Re: inequalities
Post by: Hutchoo on October 08, 2010, 08:47:56 pm
When you have two negatives on either side.

And also:
http://vcenotes.com/forum/index.php/topic,27844.msg297887.html#msg297887 -> If you needed an example.
Title: Re: inequalities
Post by: /0 on October 09, 2010, 01:44:52 am
If both sides have the same sign and you reciprocate them
Title: Re: inequalities
Post by: roberto on October 09, 2010, 02:19:01 am
i think theres a whole list of rules for different topics but the main ones are when u neg both sides or u flip both sides
Title: Re: inequalities
Post by: kriptik on October 09, 2010, 09:23:25 am
when you do logarithms with numbers less than 1 you change the direction also

(might be useful in some binomial distribution questions)

eg:




Title: Re: inequalities
Post by: lisafaustina on October 09, 2010, 07:59:00 pm
when you have something like
xln(2) > ln(3)
does that become
x<ln(3)/ln(2)
Title: Re: inequalities
Post by: TrueTears on October 09, 2010, 08:05:32 pm
Good notes on inequalities, take a read.
Title: Re: inequalities
Post by: Blakhitman on October 09, 2010, 08:32:50 pm
when you have something like
xln(2) > ln(3)
does that become
x<ln(3)/ln(2)

It's only when the argument (in the log) is less than 1 because then it is a negative value and thus dividing by negative you switch the sign.
Title: Re: inequalities
Post by: stonecold on October 09, 2010, 08:42:21 pm
Sometimes when finding solutions for quadratic inequalities I think you have to graph the parabola and through observation decide which which on of your values is greater or less than then intersection point.

This is the easiest way...
Title: Re: inequalities
Post by: Martoman on October 10, 2010, 12:38:43 am
Good notes on inequalities, take a read.

Wow as if we haven't been taught this formally in school!?!? I like these notes. Can more be found on other topics on the forum?
Title: Re: inequalities
Post by: Hutchoo on October 10, 2010, 01:12:54 am
Good notes on inequalities, take a read.

Wow as if we haven't been taught this formally in school!?!? I like these notes. Can more be found on other topics on the forum?

They're beast! I WANT SOME MORE!