x2 + y2 = 6xy
(x + y)2 - xy = 6xy
(x + y)2 = 6xy + xy
(x + y)2 = xy
log (x + y)2 = log xy
2 log (x + y) = log + log x + log y
2 log (x + y) = log 3 + log x + log y
2 log (x + y) = log 2 + log x + log y
Hence Proved