10ac-5bc+2ax-bx = 6a²-6ab-7a+7b = 4x³-4x²y+x-y = x⁴y-x³y-x+1=

10ac-5bc+2ax-bx =5c(2a-b)+x(2a-b)=(5c+x)(2a-b)
6a²-6ab-7a+7b =6a(a-b)-7(a-b)=(6a-7)(a-b)
4x³-4x²y+x-y =4x^2(x-y)+(x-y)=(4x^2+1)(x-y)
x⁴y-x³y-x+1=x^3y(x-1)-(x-1)=(x^3y-1)(x-1)