A= (2x-7)((x+3)-(4-3x))=(2x-7)(x+3-4+3x)=(2x-7)(4x-1)
(1-3x)(x+10)+(1-3x)²= (1-3x)((x+10)+(1-3x))= (1-3x)(x+10+1-3x)=(1-3x)(-2x+11)
(4+x)²+(5-2x)(x+4)=(4+x)((4+x)+(5-2x))=(4+x)(4+x+x-2x)=(4+x)( 2x+2)
(3-x)²-(3-x)(-7x+1)))= (3-x)((3-x)-(-7x+1))=(3-x)(3-x+7x-1)=(3-x)(6x+2)