(1)4x(a-b)+(b²-a²)
=4x(a-b)-(a-b)(a+b)
=(a-b)(4x-a-b)
(2)(a²+b²)²-4a²b²
=(a²+b²-2ab)(a²+b²+2ab)
=(a-b)²(a+b)²
(3)x^4+2x²-3
=x^4+2x²+1-4
=(x²+1)²-4
=(x²+1-2)(x²+1+2)
=(x²-1)(x²+3)
=(x+1)(x-1)(x²+3)
(4)(x+y)²-3(x+y)
=(x+y)(x+y-3)
(5)x³-2x²-3x
=x(x²-2x-3)
=x(x-3)(x+1)
(6)4a²-b²+6a-3b
=(4a²-b²)+6a-3b
=(2a-b)(2a+b)+3(2a-b)
=(2a-b)(2a+b+3)