🔥 Day 143 — 2026 MIT Integration Bee (Qualifying) Q9 Evaluate: ∫ x^2 sin(x) dx Classic double integration-by-parts. Set u = x^2 so the power drops on the next pass, then do parts again on ∫ x cos x. Clean, mechanical, and fast once you’ve practiced it. 👉 Hints • 1st parts: u = x^2, dv = sin x dx • 2nd parts on ∫ x cos x • Expect a combo of x sin x and cos x terms 📣 Project Mentor: free guides for AP self-study, competitions, and research/internships—see my bio for more. 💭 Drop your method be