Question

what is the right and left end behavior of the graph of f(x)=ax-x^3

Answer 1

when x is negative then f(x) is positive
when x is positive then f(x) is negative
I think when f(x) = 0 then ax = x^3 a = +/- x or x = 0

Answer 2

did you look at the graph?
https://www.desmos.com/calculator

Answer 3

correction not a but square root of a
(you have 3 zeros)