Помогите решить неравенство f'(x) меньше 0 Спс

[latex]f'(x)=-\frac{3}{x^{2}} -2x[/latex] [latex]-\frac{3}{x^{2}} -2x\ \textless \ 0[/latex] [latex]\frac{-3-2x^{3}}{x^{2}}\ \textless \ 0[/latex] [latex]-3-2x^{3}\ \textless \ 0[/latex] [latex]3+2x^{3}\ \textgreater \ 0[/latex] [latex]2x^{3}\ \textgreater \ -3[/latex] [latex]x^{3}\ \textgreater \ - \frac{3}{2}[/latex] [latex]x\ \textgreater \ \sqrt[3]{\frac{3}{2}}[/latex]