a) X^2-2x^2+x-xy^2. b) 7x^2-12x+5

a) $x^2 - 2x^2 + x - xy^2 = -x^2 + x - xy^2 = x(-x+1-y^2)$

b) $7x^2 - 12x + 5 = 7x^2 - 7x - 5x + 5 = 7x(x-1) - 5(x-1) = (7x-5)(x-1)$.

\[\begin{array}{l} a)\,\,{x^2} - 2{x^2} + x - x{y^2}\\ = - {x^2} + x - x{y^2}\\ = - x\left( {x + {y^2} - 1} \right).\\ \Rightarrow Xem\,\,lai\,\,\,de\,\,bai.\\ b)\,\,7{x^2} - 12x + 5\\ = 7{x^2} - 7x - 5x + 5\\ = 7x\left( {x - 1} \right) - 5\left( {x - 1} \right)\\ = \left( {x - 1} \right)\left( {7x - 5} \right). \end{array}\]