1. f(x) = (3x-1)(5x+3)-(3x-1)(2x-2)
=15x²+9x-5x-3-(6x²-6x-2x+2)
=15x²+4x-3-6x²+6x+2x-2
=9x²+12x-5
2. f(x) = (3x-1)(5x+3)-(3x-1)(2x-2)
= (3x-1)(5x+3-(2x-2))
= (3x-1)(5x+3-2x+2)
= (3x-1)(3x+5)
3. f(x) = 9x² + 12x - 5
= (3x + 2)² - 4 - 5
= (3x + 2)² - 9
4. a) pour resoudre f(x) = 0 on utilise la forme2
(3x-1)(3x+5) = 0
x = 1/3 ou x = -5/3
b) pour resoudre f(x) = -5 on utilise la forme1
9x²+12x-5 = -5
3x(3x+4) = 0
x = 0 ou x = -4/3
5. a) forme1 pour trouver: f(1/3) = 9/9 + 12/3 - 5 = 0
et f(√3) = 27 + 12√3 - 5 = 22 + 12√3
b) forme3 pour truver f(x) = -9 => (3x+2)²=0 => x = -2/3
