问题
填空题
方程lgx=8-2x的根x∈(k,k+1),k∈Z,则k=______.
答案
令f(x)=lgx+2x-8,则方程lgx+2x-8=0的近似解x=x0∈(k,k+1),k∈Z,即 函数f(x)的零点,
在(k,k+1)上,k∈Z,
∵f(3)=lg3+6-8<0,f(4)=lg4+8-8>0,
∴函数f(x)的零点在(3,4)上,
∴k=3,
故答案为3.
方程lgx=8-2x的根x∈(k,k+1),k∈Z,则k=______.
令f(x)=lgx+2x-8,则方程lgx+2x-8=0的近似解x=x0∈(k,k+1),k∈Z,即 函数f(x)的零点,
在(k,k+1)上,k∈Z,
∵f(3)=lg3+6-8<0,f(4)=lg4+8-8>0,
∴函数f(x)的零点在(3,4)上,
∴k=3,
故答案为3.
完形填空。 | ||||
We have two new students l our class. Their 2 are Lucy and Lily. They are twins (双胞胎). They look the same (一样). They 3 American. They are 4 the same row. This is a picture 5 our classroom. This is 6 desk and that is 7 chair. Where are 8 _ bags? They are behind the chairs. Look! 9 that under the chair. Is it a hat? 10 , it's a cat. | ||||
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