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Sagot :

Bonsoir,

1)

1- A = (7x - 3)² - 9

A = 49x² - 42x + 9 - 9

A = 49x² - 42x

2- A = (7x - 3)² - 9

A = (7x - 3 - 3) (7x - 3 + 3)

A = 7x (7x - 6)

3- 7x = 0           ou           7x - 6 = 0

x = 0                                 7x = 6

                                       x = 6/7

2)

1- B = (x - 3)² - (x - 3) (1 - 2x)

B = (- 3 - 3)² - (- 3 - 3) (1 - 2 * - 3)

B = (- 6)² - (- 6) (1 + 6)

B = 36 - (- 6) * 7

B = 36 + 42

B = 78

2- B = (x - 3)² - (x - 3) (1 - 2x)

B = x² - 6x + 9 - (x - 2x² - 3 + 6x)

B = x² - 6x + 9 - x + 2x² + 3 - 6x

B = 3x² - 13x + 12.

3- B = (x - 3)² - (x - 3) (1 - 2x)

B = (x - 3) [(x - 3) - (1 - 2x)]

B = (x - 3) (x - 3 - 1 + 2x)

B = (x - 3) (3x - 4)

4- B = (x - 3) (3x - 4) = 0

x - 3 = 0          ou           3x - 4 = 0

x = 3                              3x = 4

                                      x = 4/3

3)

1- E = (2x + 3)² - x (2x + 3)

E = 4x² + 12x + 9 - 2x² - 3x

E = 2x² + 9x + 9

2- E = (2x + 3)² - x (2x + 3)

E = (2x + 3) [(2x + 3) - x]

E = (2x + 3) (x + 3)

3- E = 2x² + 9x + 9

E = 2 * - 2/3² + 9 * - 2/3 + 9

E = 2 * - 4/9 - 18/3 + 9

E = - 8/9 - 54/9 + 81/9

E =  19/9.

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