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Développer et réduire.
A= (4x+ 2) (2x-5) -4 (x + 2)
B = (3x-1) (x -3) +2 (x-7)


Répondre :

Bonjour ,

A = ( 4x + 2 ) ( 2x - 5 ) -4 ( x + 2 )
= 4x × 2x + 4x × (-5) + 2 × 2x + 2 × (-5) -4 × X -4 × 2
= 4x^2 + ( - 20x ) + 4x + ( -20 ) - 4x - 8
= 4x^2 - 20x + 4x - 4x - 20 - 8
= 4x^2 -20x - 28

B = ( 3x - 1 ) ( x - 3 ) + 2 ( X - 7 )
= 3x × X + 3x × (-3) - 1 × x - 1 × (-3) + 2 × X + 2 × (-7)
= 3x^2 + ( -9x ) - x + 3 + 2x + (-14)
= 3x^2 - 9x - x + 2x + 3 - 14
= 3x^2 - 8x - 11

Salut,
A = (x+2) (2x - 5) - 4(x+2)
A = 2x^2 -5x+4x -10 - 4x-8 = 2x^2 - 5x - 18
B = (3x-1) (x-3) + 2 (x-7)
B = 3x^2-9x-x+3+ 2x-14 =3^2 - 8x - 11.
Bon courage.