2019 AIME I reflection notes from H

2019 AIME I — Reflection Notes from H

9 out of 15, 2 didn't finished were very close. like to know if there is better strategies for some problems.

Quick stats
• #1–5 took about 22.5 min total.
• #6 took about ~20 min (time sink).

My answers (as written)
#1: 342
#2: 029
#3: 120
#4: 122
#5: 252
#6: 090
#7: 880
#8: (very close — not finished)
#9: (wrong / crossed out)
#10: 357 (marked “silly”)
#11: ✓ (got it, but messy)
#12: (very close — basically solved but error)
#13: (basically solved, but used the wrong operation / wrong term; didn’t finish)
#14: 097
#15: (did not attempt)

Had trouble / wrong

#6 – Tried using binomial expansion, but it became too much computation (huge time sink).
#9 – Went nowhere / ended up crossing it out.
#10 – Silly mistake (need to slow down + verify).
#13 – Basically solved, but multiplied/used the wrong thing (wrong term like a_i) and didn’t finish.

Very close / almost

#8 – Very close (need to push to the finish next time).
#12 – Basically solved, but made an operation mistake (multiplied when I shouldn’t / wrong step).

Need review / improve

#11 – Got it, but I couldn’t visualize well, and the computations got messy.
#14 – Some algebra at the end felt annoying; practice finishing cleanly under time.

Not attempted

#15 – Did not attempt.

2018 AIME I reflection notes from H

2018 AIME I — Reflection Notes from H

Had trouble / wrong: #9, #10, #12, #13

Need Review / Unclear:

#9 – I got the first two terms of the final sum, but I didn’t understand / account for the double counting. a + b = 16 abd b + c = 24.

#10 – Did casework and isolated the 3’s, but wasn’t able to finish.

#12 – I got ±5 (and split into ~15 cases), but couldn’t compute after that.

#13 – Very close, but couldn’t simplify the trig at the end in the expression for the area.

2017 AIME II reflection notes from H

AIME 2017 II — Reflection Notes from H

Correct: #8, #10, #11, #12, #13

Had trouble / wrong: #9, #14, #15

Need Review / Unclear:

#9 – The “given that” statement kind of confused me. I wasn’t sure how to use it / what it was trying to tell me, so I got stuck early.

#14 – No idea how to start. I couldn’t visualize the setup, so I didn’t know what to do next.

#15 – Tried using generating functions, but it became too complicated (too many moving parts). Need a cleaner setup / approach.

2017 AIME I reflection notes from H

Correct: #8, #9, #11, #12, #14

Had trouble / wrong: #10, #13, #15

Need Review / Unclear:

#10 – Tried looking at this geometrically, but couldn’t find the right cyclic quadrilateral / setup (kept thinking about points like z₁, z₂, z₃, etc.). Need to learn how to “see” the key circle configuration faster.

#13 – I knew Q(m) would eventually become 1, but I didn’t realize it would happen at such a small value of m. This could have been done with quicker mental casework / checking small m first.

#15 – Tried using trig, but it got very complicated (too many variables). Need to practice spotting a cleaner non-trig / inequality setup sooner.

2016 AIME II reflection from H

Correct: #8, #9, #11, #12, #13, #14

Had trouble / wrong: #10, #15

Reflection / What happened:

#10 – Tried using no trig (just similar triangles + Ptolemy). Computations got messy, and I wasn’t fully confident the setup was correct.

#15 – I got pretty far into the official solution, but the step right before multiplying by Σ_i=1ⁿ(1-a_i) didn’t feel motivated to me at first (why multiply by that?). It makes more sense now, but I need to see this trick more often.

Notes:

• Cauchy–Schwarz is the right tool here and the method is clean, but it’s very tricky in execution.
• I understand the solution after reading it, but I need more problems like this to become consistent.