Răspuns :
[tex] \dfrac{1}{1} \cdot2 + \dfrac{1}{2} \cdot3 + \dfrac{1}{3} \cdot4 = [/tex]
[tex]\dfrac{2}{1} + \dfrac{3}{2} + \dfrac{4}{3}= [/tex]
[tex] \dfrac{2 \cdot6 + 3 \cdot3 + 4 \cdot2}{6} = [/tex]
[tex]\dfrac{12 + 9 + 8}{6} = [/tex]
[tex] \boxed{ \bf \dfrac{29}{6}}[/tex]