Question

diferența a celor doua sume (1+2+3+...+56)-(1+2+3+...+36)=​

Answer 1

(1+2+3+...+56)–(1+2+3+...+36)=930

=56•57:2–36•37:2

=28•57–18•37

=1 596–666

=930

Cu plăcere!!!

Answer 2

Răspuns: 930

Explicație pas cu pas:

( 1+2+3+.......+56) - (1+2+3+......+36) =

= 56 × (1+56) : 2 - 36× (1+36) : 2 =

= 56×57: 2 - 36×37: 2=

= 1596 - 666 =

= 930

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Sau:

(1+2+3+.....+56) - (1+2+3+......+36) =

= (1+2+3+......+36) - (1+2+3+.......+36) + (37+38+39+......+56) =

= 0 + 20×(37+56):2 =

= 10 × 93 =

= 930

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56 - 37 + 1 = 20 termeni are suma