1. (3x-5)(3x-5) = (3x-5)² → 2e identité remarquable de type (a-b)² = a²-2ab+b²
Donc (3x-5)(3x-5) = 9x²-30x+25
2. (x+1)(x-2)=10 si x=4
Vérification: (4+1)(4-2) = 5*2 = 10
3. 2x-(8+3x) = 2
2x-8-3x = 2
-x = 2+8
-x = 10
x = -10
4. (x-1)(x-2)-x²
= x²-2x-x+2-x²
= -3x+2
