So sánh: \(A = \frac{{{{17}^{18}} + 1}}{{{{17}^{19}} + 1}}\) và \(B = \frac{{{{17}^{17}} + 1}}{{{{17}^{18}} + 1}}\)
\(\begin{array}{l}
A = \frac{{{{17}^{18}} + 1}}{{{{17}^{19}} + 1}} < 1\\
\Rightarrow A = \frac{{{{17}^{18}} + 1}}{{{{17}^{19}} + 1}} < \frac{{{{17}^{18}} + 1 + 16}}{{{{17}^{19}} + 1 + 16}}\\
= \frac{{{{17}^{18}} + 17}}{{{{17}^{19}} + 17}} = \frac{{17\left( {{{17}^{17}} + 1} \right)}}{{17\left( {{{17}^{18}} + 1} \right)}} = B
\end{array}\)
-- Mod Toán 6
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