Question

Aratati ca numerele
A=1987+2x(1+2+3........1986) si
B=64+2x64+3x64+.........+49x64
sunt patrate perfecte.
P.S. x=inmultire

Answer 1

A=1987+2x(1+2+3........1986) =
=1987+2x1986x1987:2 =
=1987+1986x1987 =
=1987(1+1986)=
=1987x1987=
=1987²


B=64+2x64+3x64+.........+49x64=
=64(1+2+3+...+49)=
=64×49×50:2=
=64×49×25=
=8²×7²×5²=
=280²