Bonsoir
je fais donc le B
B = (-2x+1)² -3(-2x +1)(x-2)
B = (4x² +4x +1) - 3(-2x² +4x +x -2)
B = (4x² +4x +1) -3 (-2x² +5x -2)
B = (4x² +4x+1) - (-6x² +15x -6)
B = 4x² +4x +1 +6x² -15x +6
B = 10x² - 11x +7
Factorisation
(-2x+1)(-2x+1) - 3(x-2)
(-2x+1)(-2x+1 -3x +6)
(-2x+1)( -5x +7)
(-2x+1)(-5x+7) = 0
soit -2x +1 = 0 donc -2x =-1 et x = 1/2
soit -5x +7 = 0 donc -5x = -7 et x = 7/5
1/2 + 7/5 = 5/10 + 14/10 = 19/10 = 1.9
