函数f(x)=2x²-lnx的递增区间是A.(0,1/2) B.(-1/2,0)及(1/2,正无穷) C.(1/2,正无穷) D(负无穷,-1/2)及(0,1/2)
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![函数f(x)=2x²-lnx的递增区间是A.(0,1/2) B.(-1/2,0)及(1/2,正无穷) C.(1/2,正无穷) D(负无穷,-1/2)及(0,1/2)](/uploads/image/z/1988854-70-4.jpg?t=%E5%87%BD%E6%95%B0f%28x%29%3D2x%26%23178%3B-lnx%E7%9A%84%E9%80%92%E5%A2%9E%E5%8C%BA%E9%97%B4%E6%98%AFA.%EF%BC%880%2C1%2F2%EF%BC%89+B.%EF%BC%88-1%2F2%2C0%EF%BC%89%E5%8F%8A%EF%BC%881%2F2%2C%E6%AD%A3%E6%97%A0%E7%A9%B7%EF%BC%89+C.%EF%BC%881%2F2%2C%E6%AD%A3%E6%97%A0%E7%A9%B7%EF%BC%89+D%EF%BC%88%E8%B4%9F%E6%97%A0%E7%A9%B7%2C-1%2F2%EF%BC%89%E5%8F%8A%EF%BC%880%2C1%2F2%EF%BC%89)
函数f(x)=2x²-lnx的递增区间是A.(0,1/2) B.(-1/2,0)及(1/2,正无穷) C.(1/2,正无穷) D(负无穷,-1/2)及(0,1/2)
函数f(x)=2x²-lnx的递增区间是
A.(0,1/2) B.(-1/2,0)及(1/2,正无穷) C.(1/2,正无穷) D(负无穷,-1/2)及(0,1/2)
函数f(x)=2x²-lnx的递增区间是A.(0,1/2) B.(-1/2,0)及(1/2,正无穷) C.(1/2,正无穷) D(负无穷,-1/2)及(0,1/2)
递增则f'(x)=4x-1/x>0
定义域是x>0
所以两边乘x
4x²-1>0
x²>1/4
x>1/2
选C