X²-(x-1)²-(x-2)²+(x+3)². Merci d'avance ( RESULTAT ?)

Bonsoir,

x²-(x-1)²=[(x-(x-1)][x+(x-1)]=1*(2x-1)
(x+3)²-(x-2)²=[(x+3)-(x-2)][(x+3)+(x-2)]=5*(2x+1)
la somme= 2x-1+10x+5=12x+4=4(3x+1)