2a(x-y)+8b(y-x)+14c(x-y)=2a(x-y)-8b(x-y)+14c(x-y)=2(x-y)(a-4b+7c)81x^4-18x^2+1=81x^4-9x²-9x²+1=9x²(9x²-1)-(9x²-1)=(9x²-1)(9x²-1)=(9x²-1)²=(3x+1)²(3x-1...