明天上午就要 最好今天 (17 18:57:2)①已知log1227=a,求证:log616=4(3

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1.log12 27=3log12 3=a
则:4(3-a)/(3+a)=4(3-3log12 3)/(3+3log12 3)
=4(1-log12 3)/(1+log12 3)
=4log12 4/log12 36=4log36 4
=4/2 log6 4
=log6 16
2.32x=43y=126 x=126/32 y=126/43
3/x+2/y=3*32/126+2*43/126
=182/126
=91/63
======以下答案可供参考======
供参考答案1:
log12 27=3log12 3=a
则: 4(3-a)/(3+a)=4(3-3log12 3)/(3+3log12 3)=4(1-log12 3)/(1+log12 3)
=4log12 4/log12 36=4log36 4=4/2 log6 4=log6 16
额~ 第二道 我汗~