2√(1 / 8) - √(1 / 2) - (√18 + √2 - 2√(1 / 3))
= 2√(2 /.4 ²) - √(2 / 2 ²) - (√(2 × 3 ²)+ √2 - 2√(3 / 3 ²))
= 2√2 / 4 - √2 / 2 - 3√2 - √2 + 2√3 / 3
= √2 / 2 - √2 / 2 - 4√2 + (2 / 3)√3
= - 4 √2 + (2 / 3)√3
=1/2根号2-1/2根号2-(3根号2+根号2-2/3根号3)
=-4根号2+2/3根号3