Question

Va rog dau coroana rapid!!!

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Answer 1

Răspuns:

Explicație pas cu pas:

media aritmetica  = (a + b) : 2

a + b = 1/2 + 1/3 + 1/4 + ... + 1/2015 + 1/2 + 2/3 + 3/4 + ... + 2014/2015

= (1/2 + 1/2) + (1/3 + 2/3) + (1/4 + 3/4) + ... + (1/2015 + 2014/2015)

= 2/2 + 3/3 + 4/4 + ... + 2015/2015

= 1 + 1 + 1 + ... + 1 = 2014

media aritmetica = 2014 : 2 = 1007

Answer 2

Răspuns:

1007

Explicație pas cu pas:

$a + b = \Big(\frac{1}{2} + \frac{1}{3} + \frac{1}{4} + ... + \frac{1}{2015}\Big) + \Big(\frac{1}{2} + \frac{2}{3} + \frac{3}{4} + ... + \frac{2014}{2015}\Big) =$

$= \Big( \frac{1}{2} + \frac{1}{2}\Big) + \Big( \frac{1}{3} + \frac{2}{3}\Big) + \Big( \frac{1}{4} + \frac{3}{4}\Big) + ... + \Big( \frac{1}{2015} + \frac{2014}{2015}\Big)$

$= \underbrace{\frac{2}{2} + \frac{3}{3} + \frac{4}{4} + ... + \frac{2015}{2015}}_{2014 \: \: termeni}$

$= 1 + 1 + 1 + ... + 1 = 2014$

$\implies m_{a} = \frac{a + b}{2} = \frac{2014}{2} = \bf 1007$

(între 2 și 2015 sunt: 2015 - 2 + 1 = 2014 termeni)