Bonsoir ;
Exercice n° 1 .
A = 2a + 2b = 2(a + b) .
B = 5 * x + 5 * 3 = 5(x + 3) .
C = 7y + 28 = 7y + 7 * 4 = 7(y + 4) .
D = x² + 3x = x(x + 3) .
E = 3t² + 9t = 3t(t + 3) .
F = (3t)² + 9t = 9t² + 9t = 9t(t + 1) .
Exercice n° 2 .
G = 21x - 42 = 21(x - 2) .
H = - 4 - 2a = - 2(2 + a) .
I = 4/3 y - (- 4/3) y² = 4/3 y + 4/3 y² = 4/3 y (y + 1) .
Deuxième partie .
Exercice n° 1 .
A = 7(x + 4) = 7x + 28 .
B = 7(2x - 5) + 3(- x + 2) = 14x - 35 - 3x + 6 = 11x - 29 .
C = - 9(4x + 6) + 3(6 - 7x) = - 36x - 54 + 18 - 21x = - 57x - 36 .
Réduire une expression , c'est la simplifier .
Exercice n° 2 .
J = 2a + 3 + 8a + 1 = 10a + 4 .
K = 5/2 b - 13/26 b + 1 - 5/2 a = 5/2 b - 1/2 b + 1 - 5/2 a
= 4/2 b + 1 - 5/2 a = - 5/2 a + 2b + 1 .