Question

Exercitiu complicat!!! Va rog sa ma ajutati!

Aflati nr. natural x daca: 3+6+9+.....+297=150x

Answer 1

[tex]3+6+9+...+297=150x\\ 3(1+2+3+...+99)=150x\\ 3*\frac{99*100}{2}=150x\\ 3*99*50=150x\\ 150*99=150x=\ \textgreater \ x=99[/tex]

Answer 2

dam pe 3 factor comun:
3(1+2+3+4+5+...+297:3)=150x
3(1+2+3+4+5...+99)=150x
Folosim suma lui Gauss
3[(99x100):2]=150x
3x4950=150x |: 3
4950=50x => x=4950:50=99