Tính các giá trị của biểu thức:
\(\begin{array}{l}
A = \frac{{{1^2}}}{{1.2}}.\frac{{{2^2}}}{{2.3}}.\frac{{{3^2}}}{{3.4}}.\frac{{{4^2}}}{{4.5}}\\
B = \frac{{{2^2}}}{{1.3}}.\frac{{{3^2}}}{{2.4}}.\frac{{{4^2}}}{{3.5}}.\frac{{{5^2}}}{{4.6}}
\end{array}\)
\(\begin{array}{l}
A = \frac{{{1^2}}}{{1.2}}.\frac{{{2^2}}}{{2.3}}.\frac{{{3^2}}}{{3.4}}.\frac{{{4^2}}}{{4.5}}\\
= \frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5} = \frac{{1.2.3.4}}{{2.3.4.5}} = \frac{1}{5}\\
B = \frac{{{2^2}}}{{1.3}}.\frac{{{3^2}}}{{2.4}}.\frac{{{4^2}}}{{3.5}}.\frac{{{5^2}}}{{4.6}}\\
= \frac{{2.2.3.3.4.4.5.5}}{{1.2.3.3.4.4.5.6}}\\
= \frac{{2.5}}{6} = \frac{{10}}{6} = \frac{5}{3}
\end{array}\)
-- Mod Toán 6
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