Question 804051
{{{ (1/2)*( log(x) + log(y)) }}}
{{{ (1/2)*log( x*y ) }}}
{{{ log(( sqrt(x*y))) }}}
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check:
suppose {{{ x = 100 }}} 
and {{{ y = 1000 }}}
{{{ (1/2)*( log(100) + log(1000)) }}}
{{{ (1/2)*( 2 + 3 ) }}}
{{{ 5/2 }}}
and
{{{ log( sqrt(x*y)) = log( sqrt( 100000 )) }}}
{{{ log( 316.228 ) = 5/2 }}}
OK