Find x and simplify completely

Answer:
x = [tex]6\sqrt{3}[/tex] i
Step-by-step explanation:
We can write the following equation according to Euclidian Theorem to find the value of x:
[tex]x^{2}[/tex] = 12*9 multiply 9 and 12
[tex]x^{2}[/tex] = 108 find the root of both sides
x = [tex]6\sqrt{3}[/tex] is the value of x