Answer:
a).
[tex] {x}^{2} y - 2xy + y = y( {x}^{2} - 2x + 1) \\ = y {(x - 1)}^{2} [/tex]
b).
[tex]a {x}^{2} + 4ax + 4a = a( {x}^{2} + 4x + 4) \\ = a {(x + 2)}^{2} [/tex]
c).
[tex]20x - 60 {x}^{2} + 45 {x}^{3} = 5x(4 - 12x + 9 {x}^{2} ) \\ = 5x {(3x - 2)}^{2} [/tex]
