5. x²=(√(7-2√6)-√(7+√6))²
x²=(√((√6)²-2√6+1²)-√((√6)²+2√6+1²))²
x²=((√6-1)²-(√6+1))²
x²=(√6-1-√6-1)²
x²=(-2)²
x²=4
x₁=2 x₂=-2.
8√(3/4)∨(1/3)√405
√(64*3/4)∨√(405/9)
√48>√45 ⇒
8√(3/4)>(1/3)√405.
(√3-3)/(3√2-√6)=(√3-3)(3√2-√6)/((3√2-√6)(3√2+√6)=
=(3√6-9√2-√18+3√6)/((3√2)²-(√6²))=(6√6-9√2-3√2)/(18-6)=
=(6√6-12√2)/12=√6/2-√2.