Question

Va rog mult si repede !! Va rog din suflet!!! Prin metoda lui Gauss :
S=1+2+3...+200
S=1+2+3...+999
S=1+2+3...+1450

Answer 1

1+2+3+...+n=nx(n+1):2


1+2+3+...+200=200x201:2=20100


1+2+3+...+999=999x1000:2=499500


1+2+3...+1450=1450x1451:2=1051975

Answer 2

S=1+2+3+......+200
200×(200+1):2=
=200×201:2=
=100×201=
=20100

S=1+2+3+.......+999
999×(999+1):2=
=999×1000:2=
=999×500=
=499500

S=1+2+3+.......+1450
1450×(1450+1):2=
=1450×1451:2=
=725×1451=
=1051975