2x^2 - 4x + 3
= (√2x)^2 - 2(√2x)(√2) + (√2)^2 + 1
= (√2x - √2)^2 - [√(- 1)]^2
= (√2x - √2)^2 - i^2
= (√2x - √2 + i)(√2x - √2 - i)