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

Răspuns :

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
[tex](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} [/tex]