S = 1/5 = 2/10
Vì 2/10 < 3/10 => S < 3/10 (đpcm)
Ai k mk mk k lại cho !!
\(S=\frac{\frac{1}{4}+\frac{1}{6}+\frac{1}{10}}{5\cdot\left(\frac{1}{4}+\frac{1}{6}+\frac{1}{10}\right)}\)
\(S=\frac{1}{5}\)
\(\frac{1}{5}<\frac{3}{10}\)
\(S<\frac{3}{10}\)
S=\(\frac{\frac{1}{4}+\frac{1}{6}+\frac{1}{10}}{\frac{5}{4}+\frac{5}{6}+\frac{5}{10}}\)
=\(\frac{\frac{1}{4}+\frac{1}{6}+\frac{1}{10}}{5.\left(\frac{1}{4}+\frac{1}{6}+\frac{1}{10}\right)}\)
=\(\frac{1}{5}=\frac{2}{10}<\frac{3}{10}\)