(√11-3√3)2 = (√11-3√3)(√11-3√3)
= (√11)(√11) - 3(√11)(√3) - 3(√3)(√11) + 9(√3)(√3)
= 11 - 3√33 - 3√33 + 9(3)
= 11 - 9√33 + 27
= 38 - 9√33