Factor completely. y2 - xy - 56x2

For this case we have the following expression:
 y2 - xy - 56x2
 Rewriting we have the factored expression, which is given by:
 (7x + y) (y-8x)
 Checking we have:
 7xy - 56x ^ 2 + y ^ 2 - 8xy
 y ^ 2 - xy - 56x ^ 2 (OK)
 Answer:
 The factored expression is given by:
 y2 - xy - 56x2 = (7x + y) (y-8x)