Question

arata ca numarul a este patrat perfect:a=3+6+9+....+75-75

Answer 1

a=3+6+9+....+75-75
a = [3(1+2+3+...+25)] -75
a = (3×25×26:2)-75
a = 75×13-75
a = 75(13-1)
a = 75×12
a = 900
a = 30^2 (este patrat perfect)

Answer 2

a=3+6+9+....+75-75
a=3(1+2+...+25)-75
a=3×25×26:2-75
a=75x13-75
a=975-75
a=900
a=30²