Question

(x+1)+(x+3)+...+(x+25)=338.
x=?

Answer 1

(x+1)+(x+3)+...+(x+25)=338
pasul 3-1=2
(25-1) :2+1=12+1=13 termeni cifre
13 termeni de x
termen de mijloc 1+6x2=13
(x+1)+(x+3)+...+(x+25)=338
13x+6*(1+25)+13=338
13x+156+13=338
13x=338-169
13x=169
x=13