\(\therefore {a^x} = {b^y} = {c^z} = abc = k\,({\rm{say}})\)
\( \Rightarrow \)\(a = {k^{1/x}} \Rightarrow {1 \over x} = {\log _k}a\); \(\sum\limits_{}^{} {{1 \over x} = {{\log }_k}a + {{\log }_k}b + {{\log }_k}c} = {\log _k}abc = {\log _{abc}}abc = 1\).