Bonsoir,

f(x) = (x + 2) * exp^-x

f est de la forme u * v avec u = x + 2 et v = exp^-x

u' = 1 et v' = - exp^-x

(uv)' = u'v + uv'

f'(x) = exp^-x - exp^-x * (x+2)

f'(x) = exp^-x - x * exp^-x - 2exp^-x

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

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