$$\begin{gathered} a, Cho f\left(x\right)={\left(x+10\right)}^6. Tính f\text{'}\text{'}\left(2\right) \\ b, Cho f\left(x\right)=\sin 3x . Tính f\text{'}\text{'}\left(-\frac{\mathrm{\pi }}{2}\right),f\text{'}\text{'}\left(0\right),f\text{'}\text{'}\left(\frac{\mathrm{\pi }}{18}\right) \\ Giải \\ a, Ta có f\text{'}\left(x\right)=6{\left(x+10\right)}^5,f\text{'}\text{'}\left(x\right)=30{\left(x+10\right)}^4 \\ \Rightarrow f\text{'}\text{'}\left(2\right)=30{\left(2+10\right)}^4=30.{12}^4=622080 \\ b,Ta có f\text{'}\left(x\right)=3.\cos 3x \Rightarrow f\text{'}\text{'}\left(x\right)=-9\sin 3x \\ f\text{'}\text{'}\left(\frac{-\mathrm{\pi }}{2}\right)=9\sin \left(\frac{3\mathrm{\pi }}{2}\right)=-9 \\ f\text{'}\text{'}\left(0\right)=0; f\text{'}\text{'}\left(\frac{\mathrm{\pi }}{18}\right)=-9\sin \frac{\mathrm{\pi }}{6}=-\frac{9}{2} \end{gathered}$$