Question

(x+1)+(x+2)+.....(x+41)=40x +860

Answer 1

Observam ca avem de 41 de ori x si o suma Gauss :
41x+1+2+3+...+41=40x+860
41x+(41·42)/2=40x+860
41x+861=40x+860
41x-40x=860-861
x=-1

Answer 2

$(x+1)+(x+2)+.~.~.+(x+41) = 40x +860\\\\ x*41+(1+2+...+41)=40x+860\\\\ 41x-40x=860-(1+2+...+41)\\\\ x=860- \frac{42*(41+1)}{2}\\\\ x=860- \frac{41*42}{2}\\\\ x=860-861\\\\ \bold{x=-1}$