Question

x+2x+...+21x=462
Am nevoie de Ajutor.

Answer 1

Scoti factor comun pe x : 

x (1+2+...+21)=462

In paranteza aplici teorema lui Gauss : 

x (21*22/2)=462
x*21*11=462
231*x=462
x=462 : 231
x=2

Answer 2

x+2x+...+21x=462
⇒x[1+2+3+...+21]=462
⇒x[21·22/2]=462
⇒x[21·11]=462
⇒x·231=462
⇒231x=462
⇒x=462/231
⇒x=2;