What's a function rule(in math)?

Question

What's a function rule(in math)?

Answer 1

Sometimes this just means "the function".  For example, if they give you a bunch of x values and corresponding y values, then "writing the function rule" is writing the function that takes the x values and converts them to the y values.

It could also mean just explaining what the function does in words.  For example if the function is y = 3x - 5, then the rule is "Take a number, multiply it by 3, and subtract 5 from the result."

Answer 2

like the order of fuctions?

elephants march down a street.

e=[ or { or ^

m=*multiply

d=/ divide

a=+ add

s= - subtract