Find the least integer n such that f(x) is O(x") for each of these functions. (x+3x+1)/(xx-1) (i) f(x) = (ii) f(x) = 3xx+ (log.x)4 (iii) f(x) = (x+7x log x)/(x+1) (iv) f(x) = 4x+x log(x)