CoefficientList[poly, var]
CoefficientList[poly, {var1, var2, ...}]
CoefficientList[(x + 3)^5, x]
CoefficientList[(x + y)^4, x]
CoefficientList[a x^2 + b y^3 + c x + d y + 5, x]
CoefficientList[(x + 2)/(y - 3) + x/(y - 2), x]
CoefficientList[(x + y)^3, z]
CoefficientList[a x^2 + b y^3 + c x + d y + 5, {x, y}]
CoefficientList[(x - 2 y + 3 z)^3, {x, y, z}]
CoefficientList[Series[Log[1-x], {x, 0, 9}], x]
CoefficientList[Series[2x, {x, 0, 9}], x]