(sqrt(3)-sqrt(12))^2
as a surd
(sqrt(3)-sqrt(12))^2 =
(sqrt(3)-sqrt(12)) * (sqrt(3)-sqrt(12)) =
sqrt (3) * sqrt (3) - 2 sqrt (3) *sqrt(12) + sqrt(12) * sqrt(12) =
3 - 2 sqrt (36) + 12 =
15 - 2 * 6 =
15 - 12 =
3