Question

rezilvati un n ecuatiile:0,(x1)+0,(x2)+0,(x3)+....+0,(x9)=35 supra11

Answer 1

x1/99 +x2/99 +...+x9/99 =35/11

(10x+1)/99 +(10x+2)/99 +...+(10x+9)/99=35/11

(10x+1+10x+2+...+10x+9)/99=35/11, impartim prin 11:

(10x+1+10x+2+...+10x+9)/9=35, inmultim cu 9:

10x+1+10x+2+...+10x+9=35*9

9*10x +(1+2+...9)=35*9,

1+2+...+n=n(n+1)/2, la noi n=9, 

9*10x +9*10/2=9*35, impartim prin 9:

10x +5=35

10x=30

x=3