Ответ:\(5a^2-20ab=5a(a-4b)\).\(7x^3-14x^5=7x^3(1-2x^2)\).\(3a-3b+ax-bx=3(a-b)+x(a-b)=(a-b)(x+3)\).Ответ: \(5a(a-4b)\); \(7x^3(1-2x^2)\); \((a-b)(x+3)\).