Bonsoir,

f(x) = (-x - 1) * exp^-x est de la forme u * v

u = -x - 1

u' = -1

v = exp^-x

v' = - exp^-x

(uv)' = u'v + uv'

f'(x) = -1 * exp^-x - exp^x * (-x - 1)

f'(x) = -exp^-x + x *exp^-x + exp^-x

f'(x) = x * exp^-x