Question

Rezolvati in N ecuatia
x+(x+1)+(x+2)+...+(x+11)=78

Answer 1

Explicație pas cu pas:

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

12x+1+2+...+11=78

12x+11(11+1)/2=78

12x=78-66

12x=12

x=1

Bafta!

Answer 2

$\it x+(x+1)+(x+2)+\ ...\ +(x+11)=78 \Leftrightarrow12x+1+2+...+11=78\Leftrightarrow\\ \\ \Leftrightarrow12x+66=78|_{-66} \Leftrightarrow12x=12 \Leftrightarrow x=1$