min { k sin k t ( − 2 3 t 3 − 50 ) } {\displaystyle \min \left\{{\dfrac {k}{\sin {kt}}}\left(-{\dfrac {2}{3}}t^{3}-50\right)\right\}}
k ≥ 3 20 π {\displaystyle k\geq {\dfrac {3}{20}}\pi }
4 3 t 3 + 2 a k sin k t + 100 ≥ 0 {\displaystyle {\dfrac {4}{3}}t^{3}+{\dfrac {2a}{k}}\sin {kt}+100\geq 0}
a ⋅ sin k t k ≥ − 2 3 t 3 − 50 {\displaystyle a\cdot {\dfrac {\sin {kt}}{k}}\geq -{\dfrac {2}{3}}t^{3}-50}
f ( t ) = k sin k t ( − 2 3 t 3 − 50 ) {\displaystyle f(t)={\dfrac {k}{\sin {kt}}}\left(-{\dfrac {2}{3}}t^{3}-50\right)}
tan k t = t 3 + 25 t 2 {\displaystyle \tan {kt}={\dfrac {t}{3}}+{\dfrac {25}{t^{2}}}}
F = k e q 1 q 2 r 2 = ( 8.99 × 10 9 N ⋅ m 2 ⋅ C − 2 ) ⋅ Q ( 2 × 10 − 2 m ) 2 {\displaystyle F=k_{\mathrm {e} }{\frac {q_{1}q_{2}}{r^{2}}}=\left(8.99\times 10^{9}\,\mathrm {N\cdot m^{2}\cdot C^{-2}} \right)\cdot {\dfrac {Q}{\left(2\times 10^{-2}\,\mathrm {m} \right)^{2}}}}
