If x = a + 1 , y = a 1 (a > 0), then the value of (x4 + y4 2x2y2) is a a

If x = a + 1 , y = a 1 (a > 0), then the value of (x4 + y4 2x2y

1.	If x = a + 1 , y = a 1 (a > 0), then the value of (x4 + y4 2x2y2) is a a
A.	16
B.	20
C.	10
D.	5
Answer» B. 20