If x = 1 + √ 2, then what is the value of x 4 - 4x 3 + 4x 2?

x = 1 + √2
∴ x⁴ - 4x³ + 4x² = x²(x² - 4x + 4)
= x²(x - 2)²
= (1 + √2)²(1 + √2 - 2)²
=(√2 + 1)² (√2 - 1)²
=[(√2)² - (1)²]²
=(2 - 1)² =1