Please Solve everything and show work thank you A particle moves in two dimensions under the potential energy function:

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Please Solve everything and show work thank you
A particle moves in two dimensions under the potential energy
function:
𝑈(𝑥,𝑦)=𝑘(𝑥^2 +4𝑦^2 −6𝑏𝑥−𝑏𝑦)
k is a positive constant. Show that there is only one (𝑥,𝑦)
position of equilibrium and
find that position,and prove mathematically whether that position
is stable or not