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a fost răspuns

Fie a=1/2+2/3+3/4+...+2009/2010 și b=2/4+2/6+2/8+...+2/4020.Calculati a+b

Răspuns :

Lucasela

a=1/2+2/3+3/4+...+2009/2010 ; sunt 2009 fractii

b=2/4+2/6+2/8+...+2/4020; simplificam cu 2 fiecare fractie

b=1/2+1/3+1/4+….+1/2010

a+b=1/2+1/2+2/3+1/3+3/4+1/4+….+2009/2010+1/2010

a+b=2/2+3/3+4/4+….+2010/2010

a+b=1+1+1+….+1; 2009 de 1

a+b=2009