$$\frac{y^{4n+1}}{y^n \cdot y^{2n} \cdot y^2} = \frac{y^{4n+1}}{y^{n+2n+2}} = \frac{y^{4n+1}}{y^{3n+2}} = y^{4n+1-(3n+2)} = y^{4n+1-3n-2} = y^{n-1}$$
Ответ: yⁿ⁻¹