Ответ: а) \[4y^2 + 20y + 25\]; б) \[16m^2 - n^2\]
a) \[(2y + 5)^2 = (2y)^2 + 2 \cdot 2y \cdot 5 + 5^2 = 4y^2 + 20y + 25\]
б) \[(4m - n)(4m + n) = (4m)^2 - n^2 = 16m^2 - n^2\]