Question

Efectuati 4+8+12+ ......+444 prin doua moduri

Answer 1

4 + 8 + 12 + ...... + 444 =

= 4 × ( 1 + 2 + 3 + ...... + 111 ) =

= 4 × 111 × ( 1 + 111 ) : 2 =

= 2 × 111 × 112 =

= 24 864

___________________

S = 4 + 8 + 12 + ...... + 444

S = [  ( 444 - 4 ) : 4 + 1 ] termeni × ( 4 + 444 ) : 2

S = 111 termeni × 448 : 2

S = 111 × 224

S = 24 864