The square of 2 (Y-X) - 7 (X-Y) + 6 (X-Y) - 3 (Y-X)

The square of 2 (Y-X) - 7 (X-Y) + 6 (X-Y) - 3 (Y-X)

2(y-x)²-7(x-y)+6(x-y)-3(y-x)²
=-(y-x)²-(x-y)
=-(x-y)²-(x-y)
=-(x-y)[(x-y)+1]
=(y-x)(x-y+1)