Respuesta :

Answer:

(x - y)(x - y + a)

Step-by-step explanation:

[tex](x-y)^2-a(y-x) \\ \\ = (x-y)^2 + a(x - y) \\ \\ = (x - y) \{(x - y) + a \} \\ \\ = (x - y)(x - y + a)[/tex]