Para hallar los extremos hay que resolver la ecuación
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
$$\frac{d}{d x} f{\left(x \right)} = $$
primera derivada$$2 x - \frac{15 \left(- 2 x - 30\right)}{\left(x + 15\right)^{4}} + 2 = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = - \frac{23}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2} + \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2}$$
$$x_{2} = - \frac{23}{2} - \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2}$$
Signos de extremos en los puntos:
2
_____________________________________________________________________________________________________________________________________ / _____________________________________________________________________________________________________________________________________\
/ ___________________ | / ___________________ |
/ / _______ | / / _______ |
/ 10 / 735 5*\/ 21529 686 | / 10 / 735 5*\/ 21529 686 |
/ 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- | / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- |
____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ | ____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ |
/ ___________________ / / _______ / ___________________ | / ___________________ / / _______ / ___________________ |
/ / _______ / / 735 5*\/ 21529 / / _______ | / / _______ / / 735 5*\/ 21529 / / _______ |
/ / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 | / / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 |
/ 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ | / 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ |
/ \/ 4 4 ___________________ / / \/ 4 4 ___________________ | / \/ 4 4 ___________________ / / \/ 4 4 ___________________ |
/ / _______ / / / _______ ____________________________________________________________ | / / _______ / / / _______ | _____________________________________________________________________________________________________________________________________
/ / 735 5*\/ 21529 / / / 735 5*\/ 21529 / ___________________ | / / 735 5*\/ 21529 / / / 735 5*\/ 21529 | / ___________________
/ 3 / --- + ----------- / / 3 / --- + ----------- / / _______ | / 3 / --- + ----------- / / 3 / --- + ----------- | / / _______
23 \/ \/ 4 4 \/ \/ \/ 4 4 / / 735 5*\/ 21529 10 | 23 \/ \/ 4 4 \/ \/ \/ 4 4 | / 10 / 735 5*\/ 21529 686 15
(- -- + ---------------------------------------------------------------------- + ----------------------------------------------------------------------------------------------------------------------------------------------------, -23 + / 49 + 2*3 / --- + ----------- + ------------------------ + |- -- + ---------------------------------------------------------------------- + ----------------------------------------------------------------------------------------------------------------------------------------------------| + / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- - ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------)
2 2 2 / \/ 4 4 ___________________ \ 2 2 2 / / ___________________ \/ 4 4 ____________________________________________________________ 2
/ / _______ / / _______ / ___________________ / _____________________________________________________________________________________________________________________________________\
/ / 735 5*\/ 21529 / / 735 5*\/ 21529 / / _______ | / ___________________ |
/ 3 / --- + ----------- / 3 / --- + ----------- / / 735 5*\/ 21529 10 | / / _______ |
\/ \/ 4 4 / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ | / 10 / 735 5*\/ 21529 686 |
/ / \/ 4 4 ___________________ | / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- |
/ / / _______ | ____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ |
/ / / 735 5*\/ 21529 | / ___________________ / / _______ / ___________________ |
/ / 3 / --- + ----------- | / / _______ / / 735 5*\/ 21529 / / _______ |
\/ \/ \/ 4 4 | / / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 |
| / 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ |
| / \/ 4 4 ___________________ / / \/ 4 4 ___________________ |
| / / _______ / / / _______ |
| / / 735 5*\/ 21529 / / / 735 5*\/ 21529 |
| / 3 / --- + ----------- / / 3 / --- + ----------- |
|7 \/ \/ 4 4 \/ \/ \/ 4 4 |
|- + ---------------------------------------------------------------------- + ----------------------------------------------------------------------------------------------------------------------------------------------------|
\2 2 2 /
2
_____________________________________________________________________________________________________________________________________ / _____________________________________________________________________________________________________________________________________\
/ ___________________ | / ___________________ |
/ / _______ | / / _______ |
/ 10 / 735 5*\/ 21529 686 | / 10 / 735 5*\/ 21529 686 |
/ 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- | / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- |
____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ | ____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ |
/ ___________________ / / _______ / ___________________ | / ___________________ / / _______ / ___________________ |
/ / _______ / / 735 5*\/ 21529 / / _______ | / / _______ / / 735 5*\/ 21529 / / _______ |
/ / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 | / / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 |
/ 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ | / 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ |
/ \/ 4 4 ___________________ / / \/ 4 4 ___________________ | / \/ 4 4 ___________________ / / \/ 4 4 ___________________ |
/ / _______ / / / _______ ____________________________________________________________ | / / _______ / / / _______ | _____________________________________________________________________________________________________________________________________
/ / 735 5*\/ 21529 / / / 735 5*\/ 21529 / ___________________ | / / 735 5*\/ 21529 / / / 735 5*\/ 21529 | / ___________________
/ 3 / --- + ----------- / / 3 / --- + ----------- / / _______ | / 3 / --- + ----------- / / 3 / --- + ----------- | / / _______
23 \/ \/ 4 4 \/ \/ \/ 4 4 / / 735 5*\/ 21529 10 | 23 \/ \/ 4 4 \/ \/ \/ 4 4 | / 10 / 735 5*\/ 21529 686 15
(- -- + ---------------------------------------------------------------------- - ----------------------------------------------------------------------------------------------------------------------------------------------------, -23 + / 49 + 2*3 / --- + ----------- + ------------------------ + |- -- + ---------------------------------------------------------------------- - ----------------------------------------------------------------------------------------------------------------------------------------------------| - / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- - ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------)
2 2 2 / \/ 4 4 ___________________ \ 2 2 2 / / ___________________ \/ 4 4 ____________________________________________________________ 2
/ / _______ / / _______ / ___________________ / _____________________________________________________________________________________________________________________________________\
/ / 735 5*\/ 21529 / / 735 5*\/ 21529 / / _______ | / ___________________ |
/ 3 / --- + ----------- / 3 / --- + ----------- / / 735 5*\/ 21529 10 | / / _______ |
\/ \/ 4 4 / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ | / 10 / 735 5*\/ 21529 686 |
/ / \/ 4 4 ___________________ | / 98 - ------------------------ - 2*3 / --- + ----------- + ---------------------------------------------------------------------- |
/ / / _______ | ____________________________________________________________ / ___________________ \/ 4 4 ____________________________________________________________ |
/ / / 735 5*\/ 21529 | / ___________________ / / _______ / ___________________ |
/ / 3 / --- + ----------- | / / _______ / / 735 5*\/ 21529 / / _______ |
\/ \/ \/ 4 4 | / / 735 5*\/ 21529 10 / 3 / --- + ----------- / / 735 5*\/ 21529 10 |
| / 49 + 2*3 / --- + ----------- + ------------------------ / \/ 4 4 / 49 + 2*3 / --- + ----------- + ------------------------ |
| / \/ 4 4 ___________________ / / \/ 4 4 ___________________ |
| / / _______ / / / _______ |
| / / 735 5*\/ 21529 / / / 735 5*\/ 21529 |
| / 3 / --- + ----------- / / 3 / --- + ----------- |
|7 \/ \/ 4 4 \/ \/ \/ 4 4 |
|- + ---------------------------------------------------------------------- - ----------------------------------------------------------------------------------------------------------------------------------------------------|
\2 2 2 /
Intervalos de crecimiento y decrecimiento de la función:Hallemos los intervalos donde la función crece y decrece y también los puntos mínimos y máximos de la función, para lo cual miramos cómo se comporta la función en los extremos con desviación mínima del extremo:
Puntos mínimos de la función:
$$x_{1} = - \frac{23}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2} + \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2}$$
Puntos máximos de la función:
$$x_{1} = - \frac{23}{2} - \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2}$$
Decrece en los intervalos
$$\left(-\infty, - \frac{23}{2} - \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2}\right] \cup \left[- \frac{23}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2} + \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2}, \infty\right)$$
Crece en los intervalos
$$\left[- \frac{23}{2} - \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2}, - \frac{23}{2} + \frac{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}}{2} + \frac{\sqrt{- 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} - \frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + \frac{686}{\sqrt{\frac{10}{\sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}}} + 2 \sqrt[3]{\frac{5 \sqrt{21529}}{4} + \frac{735}{4}} + 49}} + 98}}{2}\right]$$