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1+2+........+50 supra 4+8+......+800

Răspuns :

(1+2+..+50)/4(1+2+...+200)=
=50x51:2/4x200x201:2
=1275/80400
=17/1072
Salut,

(1+2+...+50)/(4+8+...+800)

1+2+...+50 → suma lui Gauss : 50(50+1)/2 = 50•51/2 = 25•51 = 1275.

4+8+...+800 = 4(1+2+...+200) → suma lui Gauss :200(200+1)/2 = 200•201/2 = 100•201 = 20100.

4•20100 = 80400.


(1+2+...+50)/(4+8+...+800) =
=1275/80400 = 51/3216 (am simplificat prin 25).


Succes! :3