27^1/3-1/2^log₂6-2lg1/4+4lg5
=(3^3)^(1/3)-1/6-2lg2^(-2)+4lg5
=3-1/6-2*(-2)lg2+4lg5
=17/6+4(lg2+lg5)
=17/6+4lg10
=17/6+4
=41/6
a^(logab)=b