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Pls raspuns :
2+4+...+50+52 =


Răspuns :

2+4+6+...+52=
=2×(1+2+3+...+26)=
=2×[26×(26+1)]÷2=
=26×27=
=702
2+4+...+52=
=2(1+2+...+26)=
=2×26×27:2=
=2×351=
=702