C3 maths

has factor formulae ever come up

I'm currently learning c3 lol..

Oh okay, im doing the same as i need to get it done and dusted for A2 FM, chapter 7 of heinemman is such a pisstake sometimes

I haven't got that far, I'm on chapter 2 of the heinemann and a little stuck

oh okay, im assuming functions, i suggest using hegartymaths for it

The first point on the summary of page 30 may help. It says that a function is a special mapping such that every element of the domain is mapped to exactly one element in the range. In english, that's if you are given a function and a set of numbers that you can definitely put in (eg between -10 and 10, any whole number), you get one number out, which you can't get by putting any other valid number in.

To give you some examples, think of the line y=x between 0 and 5. For every number between 0 and 5, you get exactly 1 'unique' number out. Eg if you put in 3 you definitely get something out, which is 3, and you can't get it any way else (eg putting in 4 won't give you 3).

Now think of y=x^2 between -5 and 5. This breaks one of the rules for a function. If you put in -5, you get the same out as if you put in 5, so the output is not 'unique'. How can you change this? By changing the domain, which is what you can put in, between 0 and 5, so putting in -5 etc won't be possible. A helpful way to do it is if you draw a graph of a function, if any y value has two different x values then it's not a function.

Now think about 1/x between -5 and 5. This breaks one of the rules of a function. Not every value in the domain can be mapped to the range. Why? Because 1/0 is undefined.

If some of that is helpful and other bits aren't, feel free to ask.