Développer : F= 49-(3x+2)²
F = 49-9x²+12x+4
F = -9x²+12x+53
A =(3x+2)²
A = 9x²+12x+4
Factoriser : F = 49-(3x+2)²
F = 49-(3x+2)(3x+2)
F = 49-9x²+6x+6x+4
F = -9x²+12x+45
F pour x= 5/3
F = -9*5/3+12*5/3+45
F = -45/3+60/3+45
F = 15/3+45
F = 15/3+135/3
F = 150/3 = 50.
voilà :)
