\(a+\frac{b}{10}+\frac{c}{100}=\frac{a}{1}+\frac{b}{10}+\frac{c}{100}=\frac{1000a}{1000}+\frac{1000b}{1000}+\frac{1000c}{1000}=\frac{1000\left(a+b+c\right)}{1000}\)
Mà \(a+\frac{b}{10}+\frac{c}{100}=\frac{10}{a+b+c}\)
\(\Rightarrow\frac{1000\left(a+b+c\right)}{1000}=\frac{10}{a+b+c}\)
\(\Rightarrow a+b+c=\frac{10}{a+b+c}\)
\(\Rightarrow\left(a+b+c\right)^2=10\)
\(\Rightarrow a^2+b^2+c^2+2ab+2ac+2bc=10\)
\(\Rightarrow a^2+b^2+c^2+2\left(a^2+b^2+c^2\right)=10\)
\(\Rightarrow3\left(a^2+b^2+c^2\right)=10\)
Hình như có vấn đề hay mình làm sai nhỉ?