Câu hỏi 19Rút gọn $$ \frac{\begin{gathered} bx(a^2x^2+2a^2y^2+b^2y^2)\\ {}+ay(a^2x^2+2b^2x^2+b^2y^2) \end{gathered}}{bx+ay}. $$$a^2x^2+b^2y^2$$(ax+by)^2$$(ax+by)(bx+ay)$$2(a^2x^2+b^2y^2)$$(bx+ay)^2$