Question

Calculati a la a 2 si a la a 3
unde a=(1+0,1)+(1+0,2)+(1+0,3)+....+(1+0,9)

Answer 1

Ai ca a = (1 + 1 + 1 + ... + 1 ) + ( 1 / 10 + 2 / 10 + 3 / 10 + ... + 9 / 10 ) =>
a = 9 + ( 1 / 10 )( 1 + 2 + 3 + ... + 9 ) => a = 9 + ( 1 / 10)( 9 × 10 ) / 2 => 
a = 9 + 9 / 2 => a = 27 / 2 ( am folosit in calcul suma Gauss );
Atunci $a^{2}$ = 729 / 4 si $a^{3}$ = 19693 / 8 ;
Bafta!