Bonsoir,
A = (√5 + 1)² = (√5)² + 2√5 * 1 + 1 = 5 + 2√5 + 1 = 6 + 2√5
B = (√6 - 2)² = 6 - 4√6 + 4 = 10 - 4√6
C = (√6 + √3)² = 6 + 2 √6 √3 + 3 = 9 + 2√2.√3.√3 = 9 + 6√2
D = (3√2 - 1)² = 18 - 6√2 + 1 = 19 - 6√2
E = (√5 + √2)(√5 - √2) = (√5)² - (√2)² = 5 - 2 = 3
F = (√6 + 2) (√6 - 2) = (√6)² - 2² = 6 - 4 = 2