Question

Rezolva ecuatia x+(x+1)+(x+2)+...+(x+11)=78

Answer 1

x factor comun
 
x ori ( 1+2+..+11 ) = 78
x ori ( 11 ori 12 supra 2 ) = 78
x ori ( 132 impartit la 2 = 78
x ori 76 = 78
x = 78 impartit la 76

Answer 2

x(1+2+3+.......+11)=78
   S=11 x 12:2
   S=66
x x 66=78