Answer:
8(X^2+1)
Step-by-step explanation:
(X²+3)²-(X²-1)
(X²+3)(X²+3)-(X²-1)(X²-1)
X⁴+3X²+3X²+9-(X⁴-X²-X²+1)
X⁴+6X²+9-(X⁴-2X²+1)
X⁴+6X²+9-X⁴+2X²-1
8X²+8
