MathDB
2018 PUMaC Live Round Miscellaneous 1

Source:

January 13, 2019
PuMACLive Roundalgebrapolynomial

Problem Statement

Consider all cubic polynomials f(x)f(x) such that f(2018)=2018f(2018)=2018, the graph of ff intersects the yy-axis at height 20182018, the coefficients of ff sum to 20182018, and f(2019)>(2018)f(2019)>(2018).
We define the infinimum of a set SS as follows. Let LL be the set of lower bounds of SS. That is, L\ell\in L if and only if for all sSs\in S, s\ell\leq s. Then the infinimum of SS is max(L)\max(L).
Of all such f(x)f(x), what is the infinimum of the leading coefficient (the coefficient of the x3x^3 term)?