(a²+b²)²-36a²b²
=(a²+b²)²-(6ab)²
=(a²+b²+6ab)(a²+b²-6ab)
=(a²+6ab+9b²-8b²)(a²-6ab+9b²-8b²)
=[(a+3b)²-8b²][(a-3b)²-8b²]
=[a+(3+2√2)b][a+(3-2√2)b][a-(3-2√2)b][a-(3+2√2)b]