bjr
f(x) = (3-4x)² - (2x+1)²
image de 2 = f(2)
donc f(2) = (3 - 4*2)² - (2*2 + 1)²
tu finis
f(x) = 3² - 2*3*4x + (4x)² - ((2x)² + 2*2x*1 + 1²)
= 9 - 24x + 16x² - (4x² + 4x + 1)
= 9 - 24x + 16x² - 4x² - 4x - 1
tu finis
f(x) = (3-4x + 2x+1) (3-4x- (2x+1))
= (-2x+4) (-6x+2)
= -2(x-2)*(-2)*(3x-1)
= -4(x-2) (3x-1)
4a)
resoudre f(x) = 0
soit -4(x-2) (3x-1) = 0
x = 2 et x = 1/3
b)
résoudre 12x² - 28x + 8 = 8
12x² - 28x = 0
soit 4x(3x-7) = 0
soit x = 0
soit x = 7/3
