e la puterea minus x derivat cat imi da?
[tex]\displaystyle\bf\\Se~cere:\\\\\Big(e^{-x}\Big)'=?\\\\Folosim~formula:\\\\\Big(e^{u}\Big)'=u'\cdot e^u,~~~unde~u~este~o~functie.\\\\ \textbf{in cazul nostru }~~u=-x\\\\Rezolvare:\\\\\Big(e^{-x}\Big)'=\Big(-x\Big)'\cdot e^{-1}=-1\cdot e^{-x}=\boxed{\bf-e^{-x}}\\\\unde \Big(-x\Big)'=-1[/tex]