Bonjour . Pourriez -vous m'aider svp ? Développer PUIS réduire : A = (-3x + 5 ) (2x - 3) B = (2x - 1) (2x+1) C = (-2 + x) (x+4) D = -x (2 - x) + ( x² - 2x ) - (

Bonjour,

tu connais la règle des signes.

A = (-3x + 5 ) (2x - 3)

double distributivité

-3x* 2x = -6x²
-3x* -3 = 9x

5*2x = 10x

5* -3 = -15

=>  -6x² +9x +10x-15

=   -6x²  +19x -15

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

= 4x² +2x -2x -1

= 4x² -1

C = (-2 + x) (x+4)

= -2x -8 +x² +4x

= x²  +2x -8

D = -x (2 - x) + ( x² - 2x ) - (3x² - 4)

= -2x +x² +x² -2x -3x² +4

= -x² +4

E = 3x² - (x² - 4x + 5) - 4x (x - 3)

= 3x² -x² +4x -5 -4x² +12x

= -2x²  +16x -5

F = (2x² - 7x + 4 ) -4x (-3+2x)

= 2x² -7x +4 +12x -8x²

= -6x²  +5x +4

G= 5x (-3x - 6) - (-15x² + 18x - 6)

= -15x²  -30x  +15x² -18x +6

= -48x +6

Réponse :

bonjour

Explications étape par étape :

(*) = multiplié par

A = (-3x + 5 ) (2x - 3)

=-3x*2x -3x*-3 +5*2x -3*5

=-6x² +9x +10x -15

=-6x²+19x-15

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

=2x*2x +1*2x -1*2x -1*1

=4x² +2x -2x -1

=4x²-1

C = (-2 + x) (x+4)

=-2*x -2*4 +x*x +x*4

=-2x -8 +x²+4x

=x²+2x-8

D = -x (2 - x) + ( x² - 2x ) - (3x² - 4)

=-x*2 -x*-x + x² -2x -3x²+4

=-2x + x² +x² -2x -3x² +4

= -x² -4x +4

E = 3x² - (x² - 4x + 5) - 4x (x - 3)

=3x²-x²+4x -5 -4x*x -4x*-3

= 3x²-x² +4x -5 -4x² +12x

=-2x² +16x -5  

F = (2x² - 7x + 4 ) -4x (-3+2x)

=2x² -7x + 4 - 4x*-3 -4x*2x

=2x² - 7x + 4 +12x - 8x²

=-6x² +5x +4

G= 5x (-3x - 6) - (-15x² + 18x - 6)

=5x * -3x +5x*-6 +15x² -18x +6

= -15x² -30x -6 +15x²-18x +6

= - 48x