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Exercice 1

A = 2 (x + 3) + 7x + 2
A = 2x + 6 + 7x + 2
A = 2x + 7x + 6 + 2
A = 9x + 8

B = 4x + 3 + 7x (2x + 5)
B = 4x + 3 + 14x² + 35x
B = 14x² + 35x + 4x + 3
B = 14x² + 39x + 3

Exercice 2

3x + 2x = 5x
3x * 2 = 6x
7x * x = 7x²
5x * 2x = 10x²

Exercice 3

C = 3x² - 2x + 7
C = 3 * 2,5² - 2 * 2,5 + 7
C = 3 * 6,25 - 5 + 7
C = 18,75 + 2
C = 20,75

Ex 1 :

A = 2(x + 3) + 7x + 2
A = 2x + 6 + 7x + 2
A = 2x + 7x + 6 + 2
A = 9x + 8

B= 4x + 3 + 7x(2x + 5)
B= 4x + 3 + 14x² + 35x
B= 14x² + 35x + 4x + 3
B= 14x² + 39x +3

Ex 2 :

3x + 2x = (3 + 2)x = 5x
3x * 2 = (3 * 2)x = 6x
7x * x = 7(x * x) = 7x²
5x * 2x = (5 * 2)(x * x) = 10x²

Ex 3 :

C= 3x² - 2x + 7
C= 3 x 2,5² - 2 x 2,5 + 7
C= 3 x 6,25 - 5 + 7
C= 18,75 + 2
C= 20,75

Ex 4 :

D= 3x - 3 * 2
D= 3 * x - 3 * 2
D= 3(x - 2)

E= 5x² + 10x
E= 5x * x + 5x * 2
E= 5x(x + 2)