Question

afla valoarea lui x x+(x+1)+(x+3)+(x+5)+.....+(x+1999)=1002002

Answer 1

Adunarea este asociativa asa ca nu avem nevoie de paranteze.Facem suma lui Gauss:S=1+3+5+...+1999 S=1999+1997+...+1 Adunam cele doua sume:2S=2000+2000+...+2000;in suma avem 1000 de termeni :2S=1000•2000=2000000 S=2000000:2=1000000 in suma(cea pe care ai postat-o) avem 1000x+x=1001x;1001x+1000000=1002002 1001x=1002002-1000000 1001x=2002 x=2002/1001=2