Question

26 + 27+28 +... + 50 suma lui Gauss
3+6+9+...+150 suma lui gauss
1+2+3+...+5 suma lui gaus

Answer 1

S = 26 + 27 + 28 + ...... + 50

→ determin cati termeni are suma:  50 - 26 + 1 = 25 termeni are suma

S = 25 × ( 26 + 50 ) : 2

S = 25 × 76 : 2

S = 25 × 38

S = 950

________________

3 + 6 + 9 + ........ + 150 =

= 3 × 1 + 3 × 2 + 3 × 3 + ........ + 3 × 50 =

= 3 × ( 1 + 2 + 3 + ..... + 50 ) =

= 3 × 50 × ( 1 + 50 ) : 2 =

= 3 × 25 × 51 =

= 3 825

______________

1 + 2 + 3 + 4 + 5 = 10 + 5 = 15

= 5 × ( 1 + 5 ) : 2 =

= 5 × 6 : 2 =

= 30 : 2 =

= 15