This is one problem, and am unable to find the solution on the chegg textbook.

Find the least integer n such that f(x) 1s(x") for each of these functions a) f(x)= 2x2+x3 log x b) f(x)=3x5+ (log x)4 c) f(x) = (x4 + x2 + 1)/(x4 + 1) d) ,f(x) = (x3 + 5 log x)/(x4 + 1)