Am considerat 3a si 4b numere scrie in baza 10.
3a+4b=patrat perfect; a,b ≤ 9
3a+4b=
=30+a+40+b
=70+a+b
a+b≤18 si 70+a+b=p.p.
=> 70+a+b=81=9²
=> a+b=11
(a,b)∈ {(2,9), (3,8), (4,7), (5,6), (6,5), (7,4), (8,3), (9,2)}
verificare: 32+49=33+48=34+47=35+46=36+45=37+44=38+43=39+42=81=9²
