Express x^8 + 98*(x^4)*(y^4) + y^8 as a product of two polynomials of smaller degree with integer coefficients.
Hint... input at Wolfram|Alpha: Computational Knowledge Engine ... see below
You have probably noticed that the expression to be factored has no term. This leads to the conclusion that (using the above factorization proposed by topsquark) a = -d. Similarly, we find that c = -f. This should simplify things, if only slightly.