Réponse :
Bonsoir;
Explications étape par étape
a) (x+1)(x+2) + ( x+3) ( x-1)
x² +x+2x+2 + x² +3x -x -3 = 2x² +5x -1
b) (a +3)(a+1) + (a-1)(2a +1) = a² +3a +a +3 +2a² -2a +a -1 = 3a² + 3a +2
c) (x +2) ( x-3) - ( x+1)(x+2) = x² +2x -3x -6 -( x² +x +2x +2) =
x² -x -6 -x² -3x -2 = -4x -8 = -4( x +2)
d) (a-1)( 2a +2) - ( a-2) ( 2a -4) = 2(a-1) (a+1) -2(a-1)( a-2)
= 2(a-1) ((a+1) -(a-2) = 2(a -1) ( a+1-a +2)
= 2(a+1) ( 3) = 6( a+1)
