x = ( √2 + 1) / ( √2 -1) ·(√2 +1) + (√2 -1) / ( √2 +1 )· (√2 -1)
x = (√2 + 1) / [ √2² - 1² ] + (√2 -1) / [√2² -1² ]
√2² - 1² = 2 -1 =1
x = √2 +1 + √2 -1 = 2√2
x·(√8 - √2) = x·√2·(√4 - 1) = 2√2 ·√2 · ( 2 -1) = 2√4 ·1 = 2·2 = 4
y = √2·(√4 + 1) / √2 = √4 + 1 = 2 +1 = 3
x² - y = (2√2)² - 3 = 8 -3 = 5
