- A$ - {\left( {\frac{{{d^2}y}}{{d{x^2}}}} \right)^{ - 1}}{\left( {\frac{{dy}}{{dx}}} \right)^{ - 3}}$
- B$\;\left( {\frac{{{d^2}y}}{{d{x^2}}}} \right){\left( {\frac{{dy}}{{dx}}} \right)^{ - 2}}$
- ✓$ - \left( {\frac{{{d^2}y}}{{d{x^2}}}} \right){\left( {\frac{{dy}}{{dx}}} \right)^{ - 3}}$
- D$\;{\left( {\frac{{{d^2}y}}{{d{x^2}}}} \right)^{ - 1}}$