Question

How do you write a rule for a function

Answer 1

Ok let's start with an example

x y
1 3
2 6
3 9
4 12
5 15

ok first you would figure out what are you doing in "x"? you are adding 1.
what are you doing in "y"? you are adding 3.

so you put the output (3) over the input (1)

so it would be 3/1... which equals 3. so that would be 3x. you would multiply that by the input. so 1 times 3 is 3. and 2 times 3 is 6, ect ect. get it?

OK LET'S GO TO A HARDER ONE!!!

x y
1 3
2 7
3 11
4 15
5 19

ok so ask your self what is "x and y" doing? well x is adding 1 and y is adding 4 right?

so you put 4 over 1 which would be 4/1= 4x.

so multiply that by the input, for example: 4 times 1 is 4 right? but its not 3! so what do you have to do to 4 to get to 3? SUBTRACT 1! another example: 4 times 2 is 8 right? but its 7! You subtract one to get to 7!

So the rule would be: 4x - 1

get it? i know this is long but it will really help you, if you want to get an A+, listen to me! :)

Read more: http://wiki.answers.com/Q/How_do_you_write_a_function_rule#ixzz1VK75eHTc