We can factor this polynomial using a method known as substitution. We can let y = x^2, which gives us:
y^2 + 12y + 32
This quadratic polynomial can be factored as follows:
(y + 4)(y + 8)
Substituting back y = x^2, we get:
(x^2 + 4)(x^2 + 8)
Therefore, the completely factored form of the polynomial x^4 + 12x^2 + 32 is:
(x^2 + 4)(x^2 + 8)