Question

1+2+.............+10 folosind proprietățile adunarii

Answer 1

1 + 2 + 3 + 4 + 5 + 6 + 8 + 9 + 10 =

= ( 1 + 10 ) + ( 2 + 9 ) + ( 3 + 8 ) + ( 4 + 7 ) + ( 5 + 6 ) =  → asociativitatea adunarii

= 11 + 11 + 11 + 11 + 11 =

= 5 x 11 =

= 55

_____________________________

sau:

= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + ( 5 + 10 ) = → asociativitatea adunarii

= 10 + 10 + 10 + 10 + 15 =

= 55