设a,b,c∈R,且3^a=4^b=6^c,则A.1/c=1/a+1/bb.2/c=2/a+1/bc.1/c=2/a+2/bd.2/c=1/a+2/b

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设a,b,c∈R,且3^a=4^b=6^c,则A.1/c=1/a+1/bb.2/c=2/a+1/bc.1/c=2/a+2/bd.2/c=1/a+2/b
设a,b,c∈R,且3^a=4^b=6^c,则
A.1/c=1/a+1/b
b.2/c=2/a+1/b
c.1/c=2/a+2/b
d.2/c=1/a+2/b

设a,b,c∈R,且3^a=4^b=6^c,则A.1/c=1/a+1/bb.2/c=2/a+1/bc.1/c=2/a+2/bd.2/c=1/a+2/b
B
令3^a=4^b=6^c=X;A=LGX;
A/a=LG3;A/b=LG4;A/c=LG6;
A*2/a=2LG3;A/b=LG4;A*2/c=2LG6;
得2/a+1/b=LG36=2/c

设3^a=4^b=6^c=m (然后取对数)
∴3^a=m ==> log(m)(3^a)=1 ===>alog(m)3=1 ===>1/a=log(m)3
4^b=m ==> log(m)(4^b)=1 ===>blog(m)4=1 ===>1/b=log(m)4
6^c=m ==> log(m)(6^c)=...

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设3^a=4^b=6^c=m (然后取对数)
∴3^a=m ==> log(m)(3^a)=1 ===>alog(m)3=1 ===>1/a=log(m)3
4^b=m ==> log(m)(4^b)=1 ===>blog(m)4=1 ===>1/b=log(m)4
6^c=m ==> log(m)(6^c)=1 ===>clog(m)6=1 ===> 1/c=log(m)6
∴2/a+1/b=2log(m)3+log(m)4=log(m)9+log(m)4=log(m)36
2/c=2log(m)6=log(m)36
∴2/c=2/a+1/b
答案: B.2/c=2/a+1/b0| 评论
向TA求助回答者: 随缘_g00d 来自团队 中学生数理化 | 十

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