9× (5+10+15+...+200):41 =
9 × 5 (1+2+3+..........+40) :41 =
(1+2+3+..........+40) suma Gauss : S= [n(n+1)]:2=(40 ×41):2=820
9 × 5 × (40 × 41)/2 : 41=
(45 × 20 × 41) : 41 =
45 × 20 =
= 900
9x(5+10+15+...+200):41 = 900
dar √(900) =30 deci 900 se scrie ca 30²
9×(5+10+15+...+200):41 = 30² deci numarul dat reprezinta patratul lui 30!!!
