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Let  \mathrm{f(x)=(x+|x|)|x|} , Then for all x

Option: 1

f is continuous


Option: 2

\mathrm{f ~is~ differentiable~ for~ some~ x }


Option: 3

\mathrm{f^{\prime}}  is continuous


Option: 4

\mathrm{f^{\prime \prime}~ is~ continuous}


Answers (1)

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\mathrm{{ We ~have, } f(x)=\left\{\begin{array}{l} (x-x)(-x)=0, x<0 \\ (x+x) x=2 x^2, x \geq 0 \end{array}\right. \text {. }}

As is evident from the graph of f(x) that it is continuous and differentiable for all x. Also,
\mathrm{ f^{\prime}(x)= \begin{cases}0, & x<0 \\ 4 x, & x \geq 0^{\circ}\end{cases} }
Clearly, \mathrm{ f^{\prime}(x) }  is continuous for all x but it is not differentiable at x=0.

 

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shivangi.shekhar

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