Question 44

Consider the function

$$f(x) = \frac{e^{-\mid x \mid}}{max\left\{e^x, e^{-x}\right\}}, x \epsilon R$$ It follows that

Solution

For $$x<0$$ , f(x) = $$2e^x$$ and it is a continuous function with approaching the value 2 as $$x\longrightarrow\ 0$$ 

For $$x\ge\ 0$$ , f(x) = $$2e^{-x}$$ and it is a continuous function with approaching the value 2 as $$x\longrightarrow\ 0$$ 

Therefore the function is continuous.

However, $$x\longrightarrow\ 0^-$$ f'(x) = 2 but $$x\longrightarrow\ 0^+$$ f'(x) = -2

Thus it is not differentiable at exactly 1 point


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