Let f(x)=2x\displaystyle {f{{\left({x}\right)}}}={2}^{{x}}

If g(x)\displaystyle {g{{\left({x}\right)}}} is the graph of f(x)\displaystyle {f{{\left({x}\right)}}} shifted up 6 units and reflected across the y-axis, write a formula for g(x)\displaystyle {g{{\left({x}\right)}}}