[tex] \frac{1}{2 ^{3} } + \frac{1}{ {2}^{2} \times 3} + \frac{1}{2 \times 3 {}^{2} } + \frac{1}{ {3}^{3} } [/tex]
[tex] = \frac{1}{8} + \frac{1}{4 \times 3} + \frac{1}{2 \times 9} + \frac{1}{27} [/tex]
[tex] = \frac{1}{8} + \frac{1}{12} + \frac{1}{18} + \frac{1}{27} [/tex]
Îl amplificam pe 1/8 cu 27
Pe 1/12 cu 18
Pe 1/18 cu 12
Pe1/27 cu 8
[tex] = \frac{27}{216} + \frac{18}{216} + \frac{12}{216} + \frac{8}{216} [/tex]
[tex] = \frac{45}{216} + \frac{12}{216} + \frac{8}{216} [/tex]
[tex] = \frac{57}{216} + \frac{8}{216} [/tex]
[tex] = \frac{65}{216} [/tex]
