(lg3-1/2lg5)/(2lg3-lg5)怎么算得1/2?

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(lg3-1/2lg5)/(2lg3-lg5)怎么算得1/2?
(lg3-1/2lg5)/(2lg3-lg5)怎么算得1/2?

(lg3-1/2lg5)/(2lg3-lg5)怎么算得1/2?
(lg3-1/2lg5)/(2lg3-lg5)
=(lg3-lg根号5)/(lg9-lg5)
=lg3/根号5/lg(9/5)
=lg3/根号5/lg(3/根号5)平方
=lg3/根号5/2lg(3/根号5)
=1/2

原式中的分子分母同时乘以2,得:原式=(2lg3-lg5)/[2(2lg3-lg5)]=1/2。