Răspuns:
27
Explicație pas cu pas:
a)
[tex] \frac{1}{120} + \frac{2}{120} + \frac{3}{120} + ... + \frac{119}{120} = \frac{1 + 2 + 3 + ... + 119}{120} \\[/tex]
[tex]= \frac{ \frac{119 \times 120}{2} }{120} = \bf \frac{119}{2} \\ [/tex]
b)
[tex]\frac{2}{50} + \frac{4}{50} + \frac{6}{50} + ... + \frac{48}{50} = \frac{2 + 4 + 6 + ... + 48}{50} = \\[/tex]
[tex]= \frac{2(1 + 2 + 3 + ... + 24)}{50} = \frac{2 \times \frac{24 \times 25}{2} }{50} \\[/tex]
[tex]= \frac{24 \times 25}{50} = \frac{24}{2} = \bf 12 \\ [/tex]
