Bonjour,
1) f(7) = 7² = 49
f(-11) = (-11)² = 121
f(-√3) = (-√3)² = 3
f(√2/5) = (√2/5)² = (√2)²/5² = 2/25
2) f(√5-1) = (√5)²-2(√5)(1)+1² = 5-2√5+1 = 6-2√5
f(1-√5) = (1-√5)² = 1²-2(1)(√5)+(√5)² = 1-2√5+5 = 6-2√5
on remarque que f(√5-1) = f(1-√5)
3) de la même façon que f(√5-1) = f(1-√5) on a :
f(-3+√7) = f(3-√7)
f(3-√7) = (3-√7)² = 3²-2(3)(√7)+(√7)² = 9-6√7+7 = 16-6√7
4) f(√18+√98) = (√18+√98)²
= (√18)²+2(√18)(√98)+(√98)²
= 18 + 2(√1764) + 98
= 18 + 2(42) + 98
= 200
