$($I need step by step solution only with proper explanation and solving of each and every step $)$ Show that stability criteria must satisfy the following equations:

$(\frac{de{l}^{2}G}{del{T}^2}{)}_{P}0$

$(\frac{de{l}^{2}G}{del{P}^2}{)}_{T}0$

$(\frac{de{l}^{2}G}{del{T}^2})(\frac{de{l}^{2}G}{del{P}^2})-(\frac{de{l}^{2}G}{\text{d}\text{e}\text{l}\text{T}\text{d}\text{e}\text{l}\text{P}}{)}^{2}0$