3的x次方=2,12的y次方=8,则1/x+3/y=则1/x－3/y=

网友回答

3^x=2,12^y=8
∴ x=log3(2),y=log12(8)
∴ 1/x=log2(3),1/y=log8(12)
∴ 1/x-3/y
=log2(3)-3log8(12)
=log2(3)-log2³(12³)
=log2(3)-log2(12)
=log2(3/12)
=log2(1/4)
=-2