If (x ^ 2 + y ^ 2) (x ^ 2 + y ^ 2-1) - 12 = 0 and X, y are real numbers, then x ^ 2 + y ^ 2 =?

If (x ^ 2 + y ^ 2) (x ^ 2 + y ^ 2-1) - 12 = 0 and X, y are real numbers, then x ^ 2 + y ^ 2 =?

x^2+y^2=t
t(t-1)-12=0
t=4