Найдите производную: f(x)= ctgx^3-7x f(x)=-6x^2×cosx^3 f(x)=-9tg(10x)

3) dy/dx=f'(x)
$\frac{dy}{dx} = - 9\times \frac{1}{ {cos}^{2}10x } \times 10 = \\ =-\frac{90}{ {cos}^{2}10x }$
1)
$\frac{dy}{dx} = - \frac{1}{ {sin}^{2} {x}^{3} } \times 3 {x}^{2} - 7 = \\ = - \frac{3 {x}^{2} }{ {sin}^{2} {x}^{3} }-7$
2)
$\frac{dy}{dx} = - 6(2x \times cos {x}^{3} + \\ + {x}^{2} \times ( - sin {x}^{3} ) \times 3 {x}^{2} ) = \\ = - 6x(2cos {x}^{3} - 3 {x}^{3} sin {x}^{3} )$