Question 67011
x = 1+ log a bc =loga a+ loga bc
= loga abc
therefore 1/x=logabc a
similarly   y = log b abc
            z= log c abc
 (xy +yz+ zx)/xyz
=  1/z + 1/x +1/y
=   logabc c +logabc a +logabc b
= log abc  abc
=1

(xy +yz+ zx)/xyz = 1
therefore xy + yz +zx =xyz