题目
已知x,y,z大于零,3的x次方=4的y次方=6的z次方,求1/z-1/x=1/2y;比较3x;4y;6z的大小
提问时间:2020-07-18
答案
设3^x=4^y=6^z=k.(k>1)
x=log3(k)
y=log4(k)
z=log6(k)
1/z-1/x=logk(6)-logk(3)=logk(2)
1/(2y)=1/2*logk(4)=logk(2)
故:1/z-1/x=1/(2y)
1/(3x)=1/3*logk(3)=logk(3^1/3)
1/(4y)=1/4*logk(4)=logk(4^1/4)
1/(6z)=1/6*logk(6)=logk(6^1/6)
由于logk(3^1/3)>logk(4^1/4)>logk(6^1/6)
所以,1/3x>1/4y>1/6z
即3x
x=log3(k)
y=log4(k)
z=log6(k)
1/z-1/x=logk(6)-logk(3)=logk(2)
1/(2y)=1/2*logk(4)=logk(2)
故:1/z-1/x=1/(2y)
1/(3x)=1/3*logk(3)=logk(3^1/3)
1/(4y)=1/4*logk(4)=logk(4^1/4)
1/(6z)=1/6*logk(6)=logk(6^1/6)
由于logk(3^1/3)>logk(4^1/4)>logk(6^1/6)
所以,1/3x>1/4y>1/6z
即3x
举一反三
已知函数f(x)=x,g(x)=alnx,a∈R.若曲线y=f(x)与曲线y=g(x)相交,且在交点处有相同的切线,求a的值和该切线方程.
我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
奥巴马演讲不用看稿子.为什么中国领导演讲要看?
想找英语初三上学期的首字母填空练习……
英语翻译
最新试题
- 1“鸟”字旁的字有那些?
- 2等差数列-3,1,5,···的前几项之和是150?
- 3there are two ( ) on the desk.
- 4玻璃杯里有些橘子汁,用英语怎么说
- 5棱长等于1的正方体内接于一球体,则该球的表面积是多少?
- 6有更好的记忆单词的方法吗 一天40多个单词
- 7为什么相见不如怀念?
- 8Margaret was so thirsty for news of her lost child that she was almost driven mad怎么翻译?
- 9函数y=(sin(x-1))/(x^2-x)的水平渐近线和垂直渐近线,
- 10I was showing him a thing or two on the guitar.
热门考点
- 1土地的誓言写了哪两个季节的景物风情?
- 22007-2008
- 3交联PVP和聚维酮K30是一种物质吗?
- 4英语翻译
- 5上周飓风袭击了我的家乡的英文翻译
- 6I must ask him to give up smoking.改为同义句:I must ask him to ___ ___.
- 7they suggest the number of cars should be limited to stop air pollution
- 82.甲对乙说:“你给我100元,我的钱将比你多1倍.”乙对甲说:“你只要给我10元,我的钱将比你多5倍.”问甲乙两人各有多少元钱?
- 9英语翻译
- 10我是JKM公司的Tomas Black怎样翻译