\[\frac{1}{(a - b)(b - c)} - \frac{1}{(c - a)(c - b)} + \frac{1}{(c - a)(a - b)} = 0\]
\[\frac{1^{\backslash c - a}}{(a - b)(b - c)} + \frac{1^{\backslash a - b}}{(c - a)(b - c)} + \frac{1^{\backslash b - c}}{(c - a)(a - b)} = 0\]
\[\frac{c - a + a - b + b - c}{(a - b)(b - c)(c - a)} = 0\text{\ \ \ }\]
\[0 = 0\]
\[ч.т.д.\]