Bonjour,
A= x² +10x +8x +80 = x² +18x +80
B= 20x² +8x +15x +6 = 20x² +23x +6
C= 3x² +x +15x +5 = 3x² +16x +5
D= 12x² +8x +42x +28 = 12x² +50x +28
E= x² -8x -5x +40 = x² -13x +40
F= 21x² +15x -28x -20 = 21x² -13x -20
G= x² +18x + 81
H= 40x² -56x -5x +7 = 40x² -61x +7
I = 2x² +2x +3x +3 +5x -3 = 2x² +10x
J= 4y² -11y -20y +66 -1 +35y = 4y² +4y +65
K= 9t² -42t +49 + t² +2t -6t -12 = 10t² -34t+ 37
L = -3u² -20u² +32u +35u -56 = -23u² +67u -56