D=(2x+5)²+(2x+5)(-3x+1)
= (2x+5) (2x+5) + (2x+5) (-3x+1)
= (2x+5) (2x+5 + (-3x) + 1)
= (2x+5) (2x + 5 -3x + 1)
= (2x+5) (-x+6)
