作业帮已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R) （1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R)（1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n的值；（2）若
来源：学生作业帮助网 编辑：作业帮 时间：2024/11/29 13:17:19
![已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R) （1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R)（1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n的值；（2）若](/uploads/image/z/9480576-48-6.jpg?t=%E5%B7%B2%E7%9F%A5%E5%87%BD%E6%95%B0f%28x%29%3Dlog2%7B%283x%5E2%2B2x%2Bn%29%5C%28mx%5E2%2B1%29%7D%28m%2Cn%E5%B1%9E%E4%BA%8ER%29+%EF%BC%881%EF%BC%89%E8%8B%A5m%E5%B1%9E%E4%BA%8EN%2A%2Cx%E5%B1%9E%E4%BA%8ER%2C%E4%B8%94f%28x%29%E7%9A%84%E5%80%BC%E5%9F%9F%E4%B8%BA%5B1%2C2%5D%2C%E6%B1%82m%2Cn%E5%B7%B2%E7%9F%A5%E5%87%BD%E6%95%B0f%28x%29%3Dlog2%7B%283x%5E2%2B2x%2Bn%29%5C%28mx%5E2%2B1%29%7D%28m%2Cn%E5%B1%9E%E4%BA%8ER%29%EF%BC%881%EF%BC%89%E8%8B%A5m%E5%B1%9E%E4%BA%8EN%2A%2Cx%E5%B1%9E%E4%BA%8ER%2C%E4%B8%94f%28x%29%E7%9A%84%E5%80%BC%E5%9F%9F%E4%B8%BA%5B1%2C2%5D%2C%E6%B1%82m%2Cn%E7%9A%84%E5%80%BC%EF%BC%9B%EF%BC%882%EF%BC%89%E8%8B%A5)
已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R) （1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R)（1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n的值；（2）若
已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R) （1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n
已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R)
（1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n的值；
（2）若n=1,且f(x)的值域为R,求m的取值范围
已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R) （1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n已知函数f(x)=log2{(3x^2+2x+n)\(mx^2+1)}(m,n属于R)（1）若m属于N*,x属于R,且f(x)的值域为[1,2],求m,n的值；（2）若
（1）
值域为[1,2],
则2≤(3x^2+2x+n)/(mx^2+1)≤4
2mx^2+2≤3x^2+2x+n≤4mx^2+4
x属于R
A) 2mx^2+2≤3x^2+2x+n
(3-2m)x^2+2x+n-2≥0
即∆≤0,得4m+3n-2mn-7≥0且3-2m>0,m=1
所以n≥3
B)3x^2+2x+n≤4mx^2+4
（4m-3)x^2-2x+4-n≥0
即∆≤0,得16m-13-4mn+3n≥0,且4m-3>0,m=1
所以：n≤3
故得:m=1 n=3
(2)
f(x)=log2{(3x^2+2x+1)/(mx^2+1)}值域为R
得：(3x^2+2x+1)/(mx^2+1)>0
又3x^2+2x+1总是大于0
mx^2+1>0
m>-1/x^2
所以m≥0