a) Ta có:
\(f'(x) = 6(x + 10)'.(x + 10)^5=6.(x + 10)^5\)
\(f"(x) = 6.5(x + 10)'.(x + 10)^4= 30.(x + 10)^4\)
\(\Rightarrow f''(2) = 30.(2 + 10)^4 = 622 080\)
b) Ta có:
\(f'(x) = (3x)'.\cos 3x = 3\cos 3x\),
\(f"(x) = 3.[-(3x)'.\sin 3x] = -9\sin 3x\)
\(\Rightarrow f"\left ( -\dfrac{\pi }{2} \right ) = -9\sin \left ( -\dfrac{3\pi }{2} \right ) = -9\);
\(f"(0) = -9sin0 = 0\);
\(f" \left ( \dfrac{\pi }{18} \right ) = -9\sin\left ( \dfrac{\pi }{6} \right ) = -\dfrac{9}{2}\)
