How do you write a function rule?

Question

Back to school :( I need to know how to write a function rule for an input output box I know the formalua y=ax+b I think...

don't know how to use it though

Answer 1

you have to decided on the rule to get from the input numbers to the output numbers (and it has to be the same for ALL of them).

so if our t-chart looks like this:

INPUT    OUTPUT

   1..............3

   2..............5

   3..............7

   4..............9

   5.............11

then we put in an input number, multiply it by 2 and add 1 to get the output number (and it works for ALL of the pairs).

so if we say that x is the input number then f(x) is the output and our rule would look like this:

f(x) = 2x + 1

(the output is 2 times the input plus one)

this can be graphed as a straight line