\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=\frac{4}{5}\Rightarrow \frac{1}{2}+\frac{3}{10}=\frac{1}{2}+\frac{1}{4}+\frac{1}{20}=\frac{4}{5} \)
Công thức:
\(\frac{a}{b}<1\Rightarrow \frac{a}{b}=\frac{1}{k+1}+\frac{a-r}{b.\left(k+1\right)}\)
\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=\frac{4}{5}=>\frac{1}{2}+\frac{3}{10}=\frac{1}{2}+\frac{1}{4}+\frac{1}{20}=\frac{4}{5}\)