(6+√12:4)(6+√12:4)-4(6+√12:4)+6

(6+√3)(6+√3)-4(6+√3)+6
=(36+6√3+6√3+3)-24-4√3+6
=36+12√3+3-24-4√3+6
=21+8√3 (sampe sini udah bisa)
atau
=21+8(1,732)
=21+13,856
=34,856

#semoga bermanfaat