Question

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

Answer 1

(x+1)+(x+2)+...(x+41)=40x+860
x+1+x+2+x+3+...+x+41=40x+860
Numar termeni : (41-1)/1+1=40/1+1=40+1=41
41x+1+2+3+...+41=40x+860
(41x-40x)+ 41x42/2=860
x+41x21=860
x=860-861
x=-1



Sper ca te-am ajutat ! :)

Answer 2

fiind ultimul termen 41 înseamnă că
x+x+......+x=41x
41x+1+2+3+.......+41=40x+860
41x-40x=860-(1+2+.. .+41)
S=1+2+........+41
S=41+40+.....+1
adunând sumele
2S=42+42+.....+42
de 41 de ori
S= 42×41:2=21×41=861
revenind la examen
x=860-861
x=-1