Lời giải:
PT \(\Leftrightarrow \frac{x-b-c}{a}-1+\frac{x-c-a}{b}-1+\frac{x-a-b}{c}-1=0\)
\(\Leftrightarrow \frac{x-a-b-c}{a}+\frac{x-a-b-c}{b}+\frac{x-a-b-c}{c}=0\)
\(\Leftrightarrow (x-a-b-c)\left(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\right)=0\)
Nếu $\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\neq 0$: PT có nghiệm $x=a+b+c$
Nếu $\frac{1}{a}+\frac{1}{b}+\frac{1}{c}=0$: PT có vô số nghiệm.