ПОМОГИТЕ ПОЖАЛУЙСТА СРОЧНО ПРОШУ

2) а)
$25 {x}^{3} {y}^{2} - 4x {y}^{4 } = x {y}^{2} (25 {x}^{2} - 4 {y}^{2} ) = x{y}^{2} (5x - 4y)(5x + 4y)$
б)
$45 - 30a + 5 {a}^{2} = 5( {a}^{2} - 6a + 9) = 5 {(a - 3)}^{2}$
3)
${(4x - 3y)}^{2} - (2x + y)(3x - 5y) = 16 {x}^{2} - 24xy + 9 {y}^{2} - (6 {x}^{2} + 3xy - 10xy - 5 {y}^{2} ) = 16 {x}^{2} - 24xy + 9 {y}^{2} - (6 {x}^{2} - 7xy - 5 {y}^{2} ) = 16 {x}^{2} - 24xy + 9 {y}^{2} - 6 {x}^{2} + 7xy + 5 {y}^{2} = 10 {x}^{2} - 17xy + 14 {y}^{2}$