Thu gọn đơn thức \(4{x^3}y\left( { - 2{x^2}{y^3}} \right).\left( { - x{y^5}} \right)\) ta được:

* Hướng dẫn giải

Ta có:

\(\begin{array}{l}4{x^3}y\left( { - 2{x^2}{y^3}} \right).\left( { - x{y^5}} \right) = 4.\left( { - 2} \right){x^3}.{x^2}.\left( { - x} \right).y.{y^3}.{y^5}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 4.\left( { - 2} \right).\left( { - 1} \right).{x^6}.{y^9}\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 8.{x^6}{y^9}\end{array}\)

Chọn B