Bonjour !
A = 54-18a = 3*18 - a*18 = 18(3-a)
B = -49 + 21x = 7*(-7) + 7*(3x) = 7(-7+3x)
C = -36z + 63 = 9*(-4z) + 9*7 = 9(-4z+7)
D = 5b + 25 = 5*b + 5*5 = 5(b*5)
E = 3x² + x = x(3x) + x*1 = x(3x+1)
F = 8t² + 2t = 2t(4t) + 2t*1 = 2t(4t+1)
G = -x + 3x² = x * (-1) + x(3x) = x(-1+3x)
H = 3y² + 9y² = 3y²*1 + 3y²*3 = 3y²(1+3) donc en fait 3y²*4 = 12y²
Voilà.
