$$f' = \dfrac{e^{-5x} * cos(3x)-e^{-5x}*[cos(3x)]'}{cos^2(3x)}$$

$${ df(x)} over { dx } = { { e^{(-5x)'} } * cos( 3x) - e^{-5x} * [ cos(3x) ]' } over { cos^2(3x) } = { e^{-5x}*(-5 * cos(3x) 3sen(-3x))} over { cos^2(3x) } }$$


## 2.
$$
\large
y=x^3 \cdot(\sqrt{x} + x^2)
$$
$$
y=x^3 \cdot(x^{\frac{1}{2}} + x^2)
$$
$$
y=x^{\frac{3}{2}} + x^5
$$
$$
y=x^{\frac{7}{2}} + x^5
$$