Qualification > Math

Functions

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Flamed-Ghoust:
Hello all, i find functions  pretty confusing, please be kind enough to help me with them and explain when are they used and a few examples will be pretty helpful too.
I use the book (IGCSE mathematics written by Karen Morrison), i don't go to school and this is why I cant ask a teachermy exams are this may so please please help me

Thank you in advance

Centrino:
OK, maybe I'm a lil' late but this can be saved for future ref. so, heres a link for learning about Functions:
http://www.mathsisfun.com/sets/function.html

-it helped me when I forgot how to do it :P and you also need to know about inverse functions:
http://www.mathsisfun.com/sets/function-inverse.html

-It's easier to find out the inverse if you use algebra, like this(also already shown in the link I gave) :

                        The function:  f(x) = 2x+3
                   Put "y" for "f(x)":   y    = 2x+3
     Subtract 3 from both sides:  y-3= 2x
           Divide both sides by 2:  (y-3)/2 = x
                         Swap sides:  x =   (y-3)/2
Solution (put "f-1(y)" for "x" and replace y in "(y-3)/2" with "x") :  f-1(y) = (x-3)/2
 
-they're used whenever u see a format like this: f(x)=bla+bla (in questions the 'f' can be replaced with any letter, 'x' can sumtimes be given as a number, and it doesnt have to be addition. depends on their question)

Hope this helps :D

Flamed-Ghoust:
so basically in the example u just placed instead of it being y= i am supposed to make it it x=?? because if it is that simple i seriously dont know how will i end up, i am repeating my IGCSE math oct/nov in the hope of getting an A* even though i got a B so please any small tip can be useful

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