优优班--学霸训练营 > 知识点挑题
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            • 1.
              若\(f(x)= \begin{cases} \overset{x^{2},(x\geqslant 0)}{-x,(x < 0)}\end{cases}\),则\(f[f(-2)]=(\)  \()\)
              A.\(2\)
              B.\(3\)
              C.\(4\)
              D.\(5\)
            • 2.

              \(12.\) 函数\(f(x)=\begin{cases} \left| x \right|-2, & x\leqslant 0, \\ 2x-6+\ln x, & x > 0 \end{cases}\)的零点个数是     

            • 3.
              已知函数\(f\left( x \right)=\begin{cases} & {{\log }_{2}}x,\left( x > 0 \right) \\ & {{3}^{x}},\left( x\leqslant 0 \right) \end{cases}\),则\(f\left[ f\left( \dfrac{1}{2} \right) \right]\)的值是\((\)    \()\)

              A.\(3\)
              B.\(\dfrac{1}{3}\)
              C.\(-3\)
              D.\(-\dfrac{1}{3}\)
            • 4.

              函数\(f\left( x \right)=\begin{cases} x+1, \\ -x+3, \end{cases}\) \(\begin{matrix} x\leqslant 1, \\ x > 1, \\\end{matrix}\)  则\(f\left( f\left( 4 \right) \right)=\)_______.

            • 5.

              若函数\(f(x){=}\begin{cases} x{+}2{,}x{ > }0 \\ x^{2}{-}1{,}x{\leqslant }0 \end{cases}\),则\(f(f({-}2)){=}\)______ .

            • 6.

              已知函数\(f(x)=\begin{cases} & {{x}^{\frac{1}{2}}},x\geqslant 4 \\ & {{2}^{x}},x < 4 \end{cases}\),则\(f[f(2)]=\)(    )

              A.\(16\)
              B.\(2\)
              C.\(\sqrt{2}\)
              D.\(4\)
            • 7.

              已知\(f(x){=}\begin{cases} x{-}5{,}x{\geqslant }6 \\ f(x{+}2){,}x{ < }6 \end{cases}\),则\(f(5)=\)   (    )

              A.\(2\)   
              B.\(3\)      
              C.\(4\)      
              D.\(5\)
            • 8.

              函数\(f(x)=\begin{cases} & 2x-{{x}^{2}},(0 < x\leqslant 3) \\ & {{x}^{2}}+6x,(-2\leqslant x\leqslant 0) \end{cases}\)的值域为\((\)    \()\)

              A.\(R\)
              B.\([-8,1]\)
              C.\([-9,1]\)
              D.\([-9,+∞)\)
            • 9.

              设函数\(f(x){=}\begin{cases} \overset{2^{1{-}x}{,}x{\leqslant }1}{1{-}\log_{2}x{,}x{ > }1} \end{cases}\),则\(f(f(4)){=}(\)  \()\)

              A.\(2\)             
              B.\(4\)             
              C.\(8\)             
              D.\(16\)
            • 10.
              已知函数\(f(x)= \begin{cases} \overset{a^{x},x > 1}{(6-a)x,x\leqslant 1}\end{cases}\),若对于任意的两个不相等实数\(x_{1}\),\(x_{2}\)都有\( \dfrac {f(x_{1})-f(x_{2})}{x_{1}-x_{2}} > 0\),则实数\(a\)的取值范围是\((\)  \()\)
              A.\((1,6)\)
              B.\((1,+∞)\)
              C.\((3,6)\)
              D.\([3,6)\)
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