С2-9d2, ax+by-ay-bx разложите на множители
C²-9d²=(c-3d)(c+3d) ax-ay+by-bx=a(x-y)+b(y-x)= =a(x-y)-b(x-y)=(x-y)(a-b)
2(c-9d) , a(x-y)+b(y-x)= a (x-y)-b(x-y)=(a-b)(x-y)