x-1=lgx必有一个根的区间是( )A,(0.1,0.2)B,(0.2,0.3)C,(0.3,0.4)D,(0.4,0.5)请解释选择理由

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x-1=lgx必有一个根的区间是( )A,(0.1,0.2)B,(0.2,0.3)C,(0.3,0.4)D,(0.4,0.5)请解释选择理由
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x-1=lgx必有一个根的区间是( )A,(0.1,0.2)B,(0.2,0.3)C,(0.3,0.4)D,(0.4,0.5)请解释选择理由
x-1=lgx必有一个根的区间是( )
A,(0.1,0.2)
B,(0.2,0.3)
C,(0.3,0.4)
D,(0.4,0.5)
请解释选择理由

x-1=lgx必有一个根的区间是( )A,(0.1,0.2)B,(0.2,0.3)C,(0.3,0.4)D,(0.4,0.5)请解释选择理由
令f(x)=lgx-x+1
f(0.1)=-1-0.1+10
所以,有一个根在(0.1,0.2)之间.
选择A

用二分法的思想
分别计算f(x)=x-1-lgx在x=0.1,0.2,0.3,0.4的值
f(0.1)>0,f(0.2)<0,f(0.3)<0,f(0.4)<0
所以零点在(0.1,0.2)内