Răspuns:
[tex] \frac{ {3}^{20} - {3}^{18} }{ {3}^{17} + {3}^{20} } = \frac{ ({3}^{2} - 1) \times {3}^{18} }{(1 + {3}^{3} ) \times {3}^{17} } = \frac{(9 - 1) \times 3}{1 + 27} = \frac{8 \times 3}{28} = \frac{2 \times 3}{7} = \frac{6}{7} [/tex]
[tex] \frac{ {3}^{23} - {3}^{21} }{ {3}^{21} + {3}^{23} } = \frac{( {3}^{2} - 1) \times {3}^{21} }{(1 + {3}^{2}) \times {3}^{21} } = \frac{9 - 1}{9 + 1} = \frac{8}{10 } = \frac{4}{5} [/tex]
Sper că te-am ajutat
