Сравните дроби:
а) $\frac{23}{126}$ и $\frac{47}{330}$;
б) $\frac{59}{396}$ и $\frac{121}{840}$.
$\frac{23}{126}$ и $\frac{47}{330}$
$
\begin{array}{r|l}
126 & 2\\
63 & 3\\
21 & 3\\
7 & 7\\
1 &
\end{array}
$
$126 = 2 * 3^2 * 7$
$
\begin{array}{r|l}
330 & 2\\
165 & 3\\
55 & 5\\
11 & 11\\
1 &
\end{array}
$
$330 = 2 * 3 * 5 * 11$
$НОК = 2 * 3^2 * 5 * 7 * 11 = 6930$
6930 : 126 = 55
$\frac{23}{126} = \frac{23 * 55}{126 * 55} = \frac{1265}{6930}$
6930 : 330 = 21
$\frac{47}{330} = \frac{47 * 21}{330 * 21} = \frac{987}{6930}$
$\frac{1265}{6930} > \frac{987}{6930}$, значит:
$\frac{23}{126} > \frac{47}{330}$
$\frac{59}{396}$ и $\frac{121}{840}$
$
\begin{array}{r|l}
396 & 2\\
198 & 2\\
99 & 3\\
33 & 3\\
11 & 11\\
1 &
\end{array}
$
$396 = 2^2 * 3^2 * 11$
$
\begin{array}{r|l}
840 & 2\\
420 & 2\\
210 & 2\\
105 & 3\\
35 & 5\\
7 & 7\\
1 &
\end{array}
$
$840 = 2^3 * 3 * 5 * 7$
$НОК = 2^3 * 3^2 * 5 * 7 * 11 = 27720$
27720 : 396 = 70
$\frac{59}{396} = \frac{59 * 70}{396 * 70} = \frac{4130}{27720}$
27720 : 840 = 33
$\frac{121}{840} = \frac{121 * 33}{840 * 33} = \frac{3993}{27720}$
$\frac{4130}{27720} > \frac{3993}{27720}$, значит:
$\frac{59}{396} > \frac{121}{840}$