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Girls in Math at Yale 2022 Mathathon Round 6

Source:

March 7, 2022
number theoryalgebrageometryYale

Problem Statement

p16 Madelyn is being paid $50\$50/hour to find useful Non-Functional Trios, where a Non-Functional Trio is defined as an ordered triple of distinct real numbers (a,b,c)(a, b, c), and a Non- Functional Trio is useful if (a,b)(a, b), (b,c)(b, c), and (c,a)(c, a) are collinear in the Cartesian plane. Currently, she’s working on the case a+b+c=2022a+b+c = 2022. Find the number of useful Non-Functional Trios (a,b,c)(a, b, c) such that a+b+c=2022a + b + c = 2022.
p17 Let p(x)=x2kp(x) = x^2 - k, where kk is an integer strictly less than 250250. Find the largest possible value of k such that there exist distinct integers a,ba, b with p(a)=bp(a) = b and p(b)=ap(b) = a.
p18 Let ABCABC be a triangle with orthocenter HH and circumcircle Γ\Gamma such that AB=13AB = 13, BC=14BC = 14, and CA=15CA = 15. BHBH and CHCH meet Γ\Gamma again at points DD and EE, respectively, and DEDE meets ABAB and ACAC at FF and GG, respectively. The circumcircles of triangles ABGABG and ACFACF meet BC again at points PP and QQ. If PQPQ can be expressed as ab\frac{a}{b} for positive integers a,ba, b with gcd(a,b)=1gcd (a, b) = 1, find a+ba + b.