Bonjour,
Rouge:
14x-21 +12 -2x =4x+7
12x - 9 = 4x+7
12x -4x = 7+9
8x = 16
x = 16/8
x = 2
Orange:
2x-6 -12x -8 = 6-16x -2
10x -14 = -16x +4
10x+16x = 14+4
26x = 18
x = 18/26
x= 9/ 13
Bleu clair:
x² +10x +25 = x² -6x +9
( identités remarquables)
x -x² +10x +6x = 9 -25
16x = -16
x = -16/16
x = -1
