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$$5 x^{4} - 12 x^{2} + 4 x - 7 = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = - \frac{\sqrt{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}}{2} + \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}}}}{2}$$
$$x_{2} = - \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}}}}{2} - \frac{\sqrt{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}}{2}$$
Signos de extremos en los puntos:
5 3 2
____________________________________________________________________________________________________________________________________________ / ____________________________________________________________________________________________________________________________________________ \ / ____________________________________________________________________________________________________________________________________________ \ / ____________________________________________________________________________________________________________________________________________ \ ____________________________________________________________________________________________________________________________________________
/ ___________________ | / ___________________ | | / ___________________ | | / ___________________ | / ___________________
/ / _______ | / / _______ | | / / _______ | | / / _______ | / / _______
/ 16 / 73 \/ 18726 8 46 | / 16 / 73 \/ 18726 8 46 | | / 16 / 73 \/ 18726 8 46 | | / 16 / 73 \/ 18726 8 46 | / 16 / 73 \/ 18726 8 46
/ -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | 7* / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + ---------------------------
/ 5 \/ 125 225 ______________________________________________________________ ___________________ ______________________________________________________________ | / 5 \/ 125 225 ______________________________________________________________ ___________________ ______________________________________________________________| | / 5 \/ 125 225 ______________________________________________________________ ___________________ ______________________________________________________________| | / 5 \/ 125 225 ______________________________________________________________ ___________________ ______________________________________________________________| / 5 \/ 125 225 ______________________________________________________________ ___________________ ______________________________________________________________
/ / ___________________ / _______ / ___________________ | / / ___________________ / _______ / ___________________ | | / / ___________________ / _______ / ___________________ | | / / ___________________ / _______ / ___________________ | / / ___________________ / _______ / ___________________
/ / / _______ / 73 \/ 18726 / / _______ | / / / _______ / 73 \/ 18726 / / _______ | | / / / _______ / 73 \/ 18726 / / _______ | | / / / _______ / 73 \/ 18726 / / _______ | / / / _______ / 73 \/ 18726 / / _______
/ / 8 / 73 \/ 18726 46 75*3 / - --- + --------- / 8 / 73 \/ 18726 46 | / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- / 8 / 73 \/ 18726 46 | | / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- / 8 / 73 \/ 18726 46 | | / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- / 8 / 73 \/ 18726 46 | / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- / 8 / 73 \/ 18726 46
/ 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 / - + 2*3 / - --- + --------- - --------------------------- | / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 / - + 2*3 / - --- + --------- - --------------------------- | | / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 / - + 2*3 / - --- + --------- - --------------------------- | | / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 / - + 2*3 / - --- + --------- - --------------------------- | / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 7* / - + 2*3 / - --- + --------- - ---------------------------
/ / 5 \/ 125 225 ___________________ / 5 \/ 125 225 ___________________ | / / 5 \/ 125 225 ___________________ / 5 \/ 125 225 ___________________ | | / / 5 \/ 125 225 ___________________ / 5 \/ 125 225 ___________________ | | / / 5 \/ 125 225 ___________________ / 5 \/ 125 225 ___________________ | / / 5 \/ 125 225 ___________________ / 5 \/ 125 225 ___________________
/ / / _______ / / _______ | / / / _______ / / _______ | | / / / _______ / / _______ | | / / / _______ / / _______ | / / / _______ / / _______
/ / / 73 \/ 18726 / / 73 \/ 18726 | / / / 73 \/ 18726 / / 73 \/ 18726 | | / / / 73 \/ 18726 / / 73 \/ 18726 | | / / / 73 \/ 18726 / / 73 \/ 18726 | / / / 73 \/ 18726 / / 73 \/ 18726
/ / 75*3 / - --- + --------- / 75*3 / - --- + --------- | / / 75*3 / - --- + --------- / 75*3 / - --- + --------- | | / / 75*3 / - --- + --------- / 75*3 / - --- + --------- | | / / 75*3 / - --- + --------- / 75*3 / - --- + --------- | / / 75*3 / - --- + --------- / 75*3 / - --- + ---------
\/ \/ \/ 125 225 \/ \/ 125 225 |\/ \/ \/ 125 225 \/ \/ 125 225 | |\/ \/ \/ 125 225 \/ \/ 125 225 | |\/ \/ \/ 125 225 \/ \/ 125 225 | \/ \/ \/ 125 225 \/ \/ 125 225
(----------------------------------------------------------------------------------------------------------------------------------------------------------- - ------------------------------------------------------------------------, |----------------------------------------------------------------------------------------------------------------------------------------------------------- - ------------------------------------------------------------------------| - 4*|----------------------------------------------------------------------------------------------------------------------------------------------------------- - ------------------------------------------------------------------------| + 2*|----------------------------------------------------------------------------------------------------------------------------------------------------------- - ------------------------------------------------------------------------| - ------------------------------------------------------------------------------------------------------------------------------------------------------------- + --------------------------------------------------------------------------)
2 2 \ 2 2 / \ 2 2 / \ 2 2 / 2 2
5 3 2
____________________________________________________________________________________________________________________________________________ / ____________________________________________________________________________________________________________________________________________\ / ____________________________________________________________________________________________________________________________________________\ / ____________________________________________________________________________________________________________________________________________\ ____________________________________________________________________________________________________________________________________________
/ ___________________ | / ___________________ | | / ___________________ | | / ___________________ | / ___________________
/ / _______ | / / _______ | | / / _______ | | / / _______ | / / _______
/ 16 / 73 \/ 18726 8 46 | / 16 / 73 \/ 18726 8 46 | | / 16 / 73 \/ 18726 8 46 | | / 16 / 73 \/ 18726 8 46 | / 16 / 73 \/ 18726 8 46
/ -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | | / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + --------------------------- | 7* / -- - 2*3 / - --- + --------- + -------------------------------------------------------------------------- + ---------------------------
______________________________________________________________ / 5 \/ 125 225 ______________________________________________________________ ___________________ | ______________________________________________________________ / 5 \/ 125 225 ______________________________________________________________ ___________________ | | ______________________________________________________________ / 5 \/ 125 225 ______________________________________________________________ ___________________ | | ______________________________________________________________ / 5 \/ 125 225 ______________________________________________________________ ___________________ | ______________________________________________________________ / 5 \/ 125 225 ______________________________________________________________ ___________________
/ ___________________ / / ___________________ / _______ | / ___________________ / / ___________________ / _______ | | / ___________________ / / ___________________ / _______ | | / ___________________ / / ___________________ / _______ | / ___________________ / / ___________________ / _______
/ / _______ / / / _______ / 73 \/ 18726 | / / _______ / / / _______ / 73 \/ 18726 | | / / _______ / / / _______ / 73 \/ 18726 | | / / _______ / / / _______ / 73 \/ 18726 | / / _______ / / / _______ / 73 \/ 18726
/ 8 / 73 \/ 18726 46 / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- | / 8 / 73 \/ 18726 46 / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- | | / 8 / 73 \/ 18726 46 / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- | | / 8 / 73 \/ 18726 46 / / 8 / 73 \/ 18726 46 75*3 / - --- + --------- | / 8 / 73 \/ 18726 46 / / 8 / 73 \/ 18726 46 75*3 / - --- + ---------
/ - + 2*3 / - --- + --------- - --------------------------- / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 | / - + 2*3 / - --- + --------- - --------------------------- / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 | | / - + 2*3 / - --- + --------- - --------------------------- / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 | | / - + 2*3 / - --- + --------- - --------------------------- / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225 | 7* / - + 2*3 / - --- + --------- - --------------------------- / 5* / - + 2*3 / - --- + --------- - --------------------------- \/ 125 225
/ 5 \/ 125 225 ___________________ / / 5 \/ 125 225 ___________________ | / 5 \/ 125 225 ___________________ / / 5 \/ 125 225 ___________________ | | / 5 \/ 125 225 ___________________ / / 5 \/ 125 225 ___________________ | | / 5 \/ 125 225 ___________________ / / 5 \/ 125 225 ___________________ | / 5 \/ 125 225 ___________________ / / 5 \/ 125 225 ___________________
/ / _______ / / / _______ | / / _______ / / / _______ | | / / _______ / / / _______ | | / / _______ / / / _______ | / / _______ / / / _______
/ / 73 \/ 18726 / / / 73 \/ 18726 | / / 73 \/ 18726 / / / 73 \/ 18726 | | / / 73 \/ 18726 / / / 73 \/ 18726 | | / / 73 \/ 18726 / / / 73 \/ 18726 | / / 73 \/ 18726 / / / 73 \/ 18726
/ 75*3 / - --- + --------- / / 75*3 / - --- + --------- | / 75*3 / - --- + --------- / / 75*3 / - --- + --------- | | / 75*3 / - --- + --------- / / 75*3 / - --- + --------- | | / 75*3 / - --- + --------- / / 75*3 / - --- + --------- | / 75*3 / - --- + --------- / / 75*3 / - --- + ---------
\/ \/ 125 225 \/ \/ \/ 125 225 | \/ \/ 125 225 \/ \/ \/ 125 225 | | \/ \/ 125 225 \/ \/ \/ 125 225 | | \/ \/ 125 225 \/ \/ \/ 125 225 | \/ \/ 125 225 \/ \/ \/ 125 225
(- ------------------------------------------------------------------------ - -----------------------------------------------------------------------------------------------------------------------------------------------------------, |- ------------------------------------------------------------------------ - -----------------------------------------------------------------------------------------------------------------------------------------------------------| - 4*|- ------------------------------------------------------------------------ - -----------------------------------------------------------------------------------------------------------------------------------------------------------| + 2*|- ------------------------------------------------------------------------ - -----------------------------------------------------------------------------------------------------------------------------------------------------------| + -------------------------------------------------------------------------- + -------------------------------------------------------------------------------------------------------------------------------------------------------------)
2 2 \ 2 2 / \ 2 2 / \ 2 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:
$$x_{1} = - \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2} + \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2}$$
Puntos máximos de la función:
$$x_{1} = - \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2} - \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2}$$
Decrece en los intervalos
$$\left(-\infty, - \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2} - \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2}\right] \cup \left[- \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2} + \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2}, \infty\right)$$
Crece en los intervalos
$$\left[- \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2} - \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2}, - \frac{\sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}{2} + \frac{\sqrt{- 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + \frac{16}{5} + \frac{8}{5 \sqrt{\left|{- \frac{46}{75 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}}} + 2 \sqrt[3]{- \frac{73}{125} + \frac{\sqrt{18726}}{225}} + \frac{8}{5}}\right|}}}}{2}\right]$$