Bonsoir;
D= (x+1)(2x-5) + (2x-5)²
= 2x² -5x +2x -5 +4x² -20x +25
= 6x² -23x +20
E=(3x-4)(2-x) - (3x-4)²
= 6x -3x² -8 +4x - ( 9x² -24x +16)
= 6x -3x² -8 +4x - 9x² +24x -16
= -12x² +34x -24
F= (x+1)²+(x + 1)(3x + 1)
= x² +2x+1 +3x²+x +3x +1
= 4x² +6x +2