To find X2, we can use the formula for finding the roots of a quadratic equation:

X2 = (-p - sqrt(p^2 - 4(1)(56)) / 2(1)

Given that X1 = -4, let's substitute it in the equation to find p:

-4 = (-p + sqrt(p^2 - 224)) / 2

Solving for p:

-8 = -p + sqrt(p^2 - 224)
-p = 8 - sqrt(p^2 - 224)
p = sqrt(p^2 - 224) - 8
p^2 = p^2 - 224
224 = 0

This is a contradiction, so there seems to be a mistake in the question.