Let x and y follow a normal bivariate probability function with means $\bar X, \bar Y$, standard deviations σ1, σ2, respectively, r the coefficient of correlation, and $\rho_1 = \bar X/\sigma_1, ...

For a quadratic equation of the form y = k (x a) 2 + b, the following diagram shows the main properties: If k > 0, the vertex is a minimum turning point If k < 0, the vertex is a maximum turning point ...