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2. tex] a) \frac{3}{11} + \frac{1}{10} ; b) \frac{1}{13} + \frac{1}{10} ; c) \frac{1}{17} + \frac{1}{10} ; d) \frac{1}{19} + \frac{1}{20} ; e) \frac{1}{13} + \frac{1}{30} ; f) \frac{1}{29} + \frac{1}{10} ; [/tex]
3. [tex] a) \frac{1}{4} + \frac{1}{16} + \frac{1}{64}; b) \frac{1}{5} + \frac{1}{25} + \frac{1}{125} ; c) \frac{1}{6} + \frac{1}{36} + \frac{1}{216} ; d) \frac{1}{7} + \frac{1}{49} + \frac{1}{343} ; [/tex]


Răspuns :

[tex]a)\frac{3}{11}+\frac{1}{10}=\frac{30+11}{110}=\frac{41}{110}; \\ \\ b)\frac{1}{13}+\frac{1}{10}= \frac{10+13}{130} = \frac{23}{130} \\ \\ c) \frac{1}{17} + \frac{1}{10}= \frac{10+17}{170}= \frac{27}{170} \\ \\ d) \frac{1}{19} + \frac{1}{20}= \frac{20+19}{380} = \frac{39}{380} \\ \\ e)\frac{1}{13} + \frac{1}{30}= \frac{30+13}{390}= \frac{43}{390} \\ \\ f) \frac{1}{29} + \frac{1}{10}= \frac{10+29}{290} = \frac{39}{290} \\ \\ [/tex]