Question 433632
{{{1/log(x, xy) + 1/log(y, xy) }}}.
Use change-of-base formula:
{{{1/log(x, xy) + 1/log(y, xy)

=1/(log(xy)/logx) + 1/(log(xy)/logy)

=logx/log(xy) + logy/log(xy)

=(logx + logy)/log(xy) = log(xy)/log(xy) = 1
}}}