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