Acubic function generally has the form f(x) = ax3 + bx2 + cx + d. if we know that for some x-value x = p we have f(p) = 0, then it must be true that x − p is a factor of f(x). since we are told that f(3) = 0, we know that is a factor.

Ifound this on google “that means that the graph of a function with direct variation has these features: it is a straight line: because the slope is the ratio y/x = k. it passes through the origin (0,0): because y = kx = k (0) = 0.” i hope this you for what your looking for