1 − ρ 2 {\displaystyle {1-\rho ^{2}}}
2 ( x 1 2 σ 1 2 − 2 ρ x 1 x 2 σ 1 σ 2 + x 2 2 σ 2 2 ) {\displaystyle 2({\frac {x_{1}^{2}}{\sigma _{1}^{2}}}-{\frac {2\rho x_{1}x_{2}}{\sigma _{1}\sigma _{2}}}+{\frac {x_{2}^{2}}{\sigma _{2}^{2}}})}
2 ( x 1 2 σ 1 2 − 2 ρ x 1 x 2 σ 1 σ 2 + x 2 2 σ 2 2 ) 1 − ρ 2 {\displaystyle {\frac {2({\frac {x_{1}^{2}}{\sigma _{1}^{2}}}-{\frac {2\rho x_{1}x_{2}}{\sigma _{1}\sigma _{2}}}+{\frac {x_{2}^{2}}{\sigma _{2}^{2}}})}{1-\rho ^{2}}}}
2 ( x 1 2 σ 1 2 − 2 ρ x 1 x 2 σ 1 σ 2 + x 2 2 σ 2 2 ) 1 − ρ 2 {\displaystyle {\sqrt {\frac {2({\frac {x_{1}^{2}}{\sigma _{1}^{2}}}-{\frac {2\rho x_{1}x_{2}}{\sigma _{1}\sigma _{2}}}+{\frac {x_{2}^{2}}{\sigma _{2}^{2}}})}{1-\rho ^{2}}}}}
