Bonsoir,
D= 4x² -8x +4 -(6x² -6x +14x -14)
= 4x² -8x +4 -6x² +6x -14x +14
=-2x² -16x +18
factoriser:
(2x-2) ( 2x-2 -3x -7)
= (2x-2) ( -x -9)
D= 0
(2x-2) ( -x -9) =0
soit
2x-2 =0
2x =2
x= 2/2
x = 1
soit
-x-9= 0
-x = 9
x= -9
x= 1
(2x-2) ( -x -9)
(2*1 -2) (-1 -9)
= (2-2 ) ( -10)
0*-10
= 0
