7:59

arcsin x + arccos x = pi/2

17:08

Solving a Quartic Equation

17:33

Find (x+y+z) [Harvard-MIT] Guts contest

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Raiz quadrada de um número imaginário

18:08

a super nice functional equation

9:55

Is x^x=0 solvable?

10:43

Solving a septic equation

17:50

1973 USAMO ( System of equations)