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Calculati:
3•(1+2+3+...+1000)+(3+4+5+...+1000)•(-3)=?
Multumesc anticipaaat! :)


Răspuns :

3x(1+2+3+1+1000)+(3+4+5+2+1000)x(-3)=
3x1007+1014x(-3)=
=3021+(-3042)=
=21
3·(1+2+3+...+1000)+(3+4+5+...+1000)·(-3)=3·(1+2)+3·(3+4+5+...+1000)-3·(3+4+5+...+1000)=
=6+(3+4+5+...+1000)·(3-3)=6+0=6