高一数学6.7题过程
4个回答
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解6由56^a=14
即a=log56(14)=log56(7)+log56(8)
=log56(7)+3log56(2)
=1/log7(56)+3log56(2)
即1/log7(56)=a-3log56(2)
即log7(56)=1/[a-3log56(2)]
7由由题知x=log5.4(3),y=log0.6(3)
故1/x-1/y
=1/(log5.4(3))-1/(log0.6(3))
=log3(5.4)-log3(0.6)
=log3(5.4/0.6)
=log3(9)
=log3(3^2)
=2
即a=log56(14)=log56(7)+log56(8)
=log56(7)+3log56(2)
=1/log7(56)+3log56(2)
即1/log7(56)=a-3log56(2)
即log7(56)=1/[a-3log56(2)]
7由由题知x=log5.4(3),y=log0.6(3)
故1/x-1/y
=1/(log5.4(3))-1/(log0.6(3))
=log3(5.4)-log3(0.6)
=log3(5.4/0.6)
=log3(9)
=log3(3^2)
=2
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