given $$h\_t=\alpha\_0+(1-\beta\_1)\epsilon^2\_{t-1}+\beta\_1Lh\_t$$ where $$Lh\_t=h\_{t-1}$$ how can I obtain $$h\_t=\alpha\_0/(1-\beta\_1)+(1-\beta\_1)\sum\_{1=0}^\inf\beta\_1^i\epsilon^2\_{t-1-i}$$?