Question 254515
The second order derivative d^2f/dx^2 of f (x)= x exp (-x) is?
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y = x*e^-x
y' = x*(-e^-x) + e^-x
{{{dy^2/dx^2 = x*e^(-x) - e^(-x)}}}
= {{{(x-1)*e^(-x)}}}