Question

if x,y,z are rational and strictly positive and if 1/x+1/y=1/z show that (x^2+y^2+z^2)^1/2 is rational ​

Answer 1

${( {x}^{2} + {y}^{2} + {z}^{2} )}^{ \frac{1}{2} }$

Is this that what we need to prove ??