je n'y arrive pas au 25 et au 26 pourriez-vous m'aider svp?

bonjour

M = (  7 x +5 ) ( 3 x - 2) + ( 7 x +5) ( 2 x - 3)
M = ( 7 x + 5) ( 3 x - 2 + 2 x - 3)
M = ( 7 x + 5) ( 5 x - 5)

si x = 0
M = 5 x - 5 = - 25

N = ( 4 x - 5) ( x - 3 - 3 x - 1)
N = ( 4 x - 5) ( - 2 x - 4)

pour x = - 1
N = ( - 4 - 5) ( 2 - 4)
N = - 9 * - 2 = 18

Exercice 25 : 

1) M = (7x + 5) (3x - 2) + (7x + 5) (2x - 3)
M = (7x + 5) [(3x - 2) + (2x - 3)
M = (7x + 5) (3x - 2 + 2x - 3)
M = (7x + 5) (5x - 5)

2) Pour x = 0 :

M = (7x + 5) (5x - 5)
M = (7 X 0 + 5) (5 X 0 - 5)
M = (0 + 5) (0 - 5)
M = 5 X (- 5)
M = - 25

Exercice 26 : 

1) N = (4x - 5) (x - 3) - (3x + 1) (4x - 5)
N = (4x - 5) [(x - 3) - (3x + 1)
N = (4x - 5) (x - 3 - 3x - 1)
N = (4 x - 5) (- 2x - 4)

2) Pour x = - 1 :

N = (4x - 5) (- 2x - 4)
N = [(4 X (- 1) - 5] [(- 2 X (- 1) - 4]
N = (- 4 - 5) (2 - 4)
N = - 4 X 2 - 4 X (- 4) - 5 X 2 - 5 X (- 4)
N = - 8 + 16 - 10 + 20
N = 18