19、log₅³⁵+2log(½)√2-log₅(1/50)-log₅¹⁴
=log₅³⁵+log(½)²+log₅⁵º-log₅¹⁴
=(log₅⁷+log₅⁵)-log₂²+(log₅²⁵+log₅²)-(log₅⁷+log₅²)
=log₅⁵-log₂²+log₅²⁵
=1-1+2
=2
18、(lg√27+lg8-3lg√10)/lg1.2
=(3lg√3+3lg2-3lg√10)/lg1.2
=3•(lg√3+lg2-lg√10)/lg1.2
=3•lg(√3•2/√10)/lg1.2
=3•lg(√12/√10)/lg1.2
=3•lg√1.2/lg1.2
=3/2•lg1.2/lg1.2
=3/2
6题。3*2=6
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