Question

3+7+11+ . . . . . . +43
1+3+5+. . . . . +99
7+14+21+. . . . . . +2023
Pls

Answer 1

Răspuns:

Explicație pas cu pas:

3 + 7 + 11 + ..... + 43 = 253

(43 - 3 ) : 4 + 1 = 11 termeni are suma

= 11 × ( 3 + 43 ) : 2 =

= 11 × 46 : 2 =

= 11 × 23 =

= 253

_________________________

1 + 3 + 5 + .... + 99 =

( 99 - 1 ) : 2 + 1 = 98 : 2 + 1 = 50 termeni are suma

= 50 × ( 1 + 99 ) : 2 =

= 50 × 100 : 2 =

= 50 × 50 =

= 2 500

____________________

7 + 14 + 21 + ..... + 2 023 =

= 7 × ( 1 + 2 + 3 + ...... + 289 ) =

= 7 × [ 289 × ( 1 + 289 ) : 2 ] =

= 7 × ( 289 × 290 : 2 ) =

= 7 × ( 289 × 145 ) =

= 7 × 41 905 =

= 293 335