4lg2 +3lg5-lg(1/5)
=lg16+lg125-lg(1/5)
=lg[16×125÷(1/5)]
=lg(16×125×5)
=lg10000
=4
lg12.5-lg(5/8)+lg(1/2)
=lg[12.5÷(5/8)×(1/2)]
=lg[(25/2)×(1/2)×(8/5)]
=lg[(25/4)×(8/5)]
=lg10
=1
(lg4)^2 +(lg25)^2 +8lg2lg5
=(2lg2)^2 +(2lg5)^2 +8lg2lg5
=(2lg2+2lg5)^2
=(2lg10)^2
=4