Question

Va rog! Dau coroana!
2x+5+10+15+20+...+100=2413

Answer 1

2x+5+10+15+20+....+100=2413⇔2x+5(1+2+3+...........20)=2413

Dar 1+2+3+.............20 =21*20/2=21*10=210⇒2x+5*210=2413⇒2x+1050=2413⇔ 2x=2413-1050⇒2x=1363⇒x=1363/2⇒x=681,5