Hallemos los puntos de flexiones, para eso hay que resolver la ecuación
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(la segunda derivada es igual a cero),
las raíces de la ecuación obtenida serán los puntos de flexión para el gráfico de la función indicado:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
segunda derivada$$14 \left(3 x^{2} \left(3 x - 8\right)^{2} + \left(3 x - 4\right) \left(x^{3} - 4 x^{2} + 3\right)\right) \left(x^{3} - 4 x^{2} + 3\right)^{5} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 1$$
$$x_{2} = \frac{3}{2} - \frac{\sqrt{21}}{2}$$
$$x_{3} = \frac{3}{2} + \frac{\sqrt{21}}{2}$$
$$x_{4} = \frac{4}{3} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}$$
$$x_{5} = \frac{4}{3} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}$$
$$x_{6} = \frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}$$
$$x_{7} = \frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}$$
Intervalos de convexidad y concavidad:Hallemos los intervales donde la función es convexa o cóncava, para eso veamos cómo se comporta la función en los puntos de flexiones:
Cóncava en los intervalos
$$\left(\left[\frac{3}{2} + \frac{\sqrt{21}}{2}, \infty\right) \cap \left[\frac{4}{3} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}, \infty\right) \cap \left[\frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}, \infty\right)\right) \cup \left(\left(-\infty, \frac{4}{3} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}\right] \cap \left(-\infty, \frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}\right] \cap \left[\frac{3}{2} - \frac{\sqrt{21}}{2}, 1\right] \cap \left[\frac{4}{3} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}, \infty\right) \cap \left[\frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}, \infty\right)\right)$$
Convexa en los intervalos
$$\left(\left(-\infty, \frac{3}{2} - \frac{\sqrt{21}}{2}\right] \cap \left(-\infty, \frac{4}{3} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}\right] \cap \left(-\infty, \frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}\right]\right) \cup \left(\left(-\infty, \frac{4}{3} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}\right] \cap \left(-\infty, \frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}\right] \cap \left[1, \frac{3}{2} + \frac{\sqrt{21}}{2}\right] \cap \left[\frac{4}{3} - \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2} - \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} - \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2}, \infty\right) \cap \left[\frac{4}{3} + \frac{\sqrt{\frac{224}{45} - 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}} + \frac{47}{135 \sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}} - \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}}{2} + \frac{\sqrt{\frac{112}{45} + \frac{5408}{2025 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}} + 2 \sqrt[3]{\frac{8928037}{5832000} + \frac{\sqrt{627443215} i}{129600}}}}{2}, \infty\right)\right)$$