\[\eqalign{ & a]\,\,\left[ {20{x^5} - 15{x^3} + 10{x^2}} \right]:\left[ {5{x^2}} \right] \cr & \,\,\,\,\, = {{20{x^5}} \over {5{x^2}}} - {{15{x^3}} \over {5{x^2}}} + {{10{x^2}} \over {5{x^2}}} \cr & \,\,\,\,\, = 4{x^3} - 3x + 2 \cr & b]\,\,\left[ {18{x^4}{y^5} + 24{x^3}{y^4} - 5{x^2}{y^3}} \right]:\left[ {6{x^2}{y^2}} \right] \cr & \,\,\,\,\, = {{18{x^4}{y^5}} \over {6{x^2}{y^2}}} + {{24{x^3}{y^4}} \over {6{x^2}{y^2}}} - {{5{x^2}{y^3}} \over {6{x^2}{y^2}}} \cr & \,\,\,\,\, = 3{x^2}{y^3} + 4x{y^2} - {5 \over 6}y \cr} \]
Đề bài
Thực hiện phép tính:
a] \[[20{x^5} - 15{x^3} + 10{x^2}]:5{x^2}\] ;
b] \[[18{x^4}{y^5} + 24{x^3}{y^4} - 5{x^2}{y^3}]:6{x^2}{y^2}\]
Lời giải chi tiết
\[\eqalign{ & a]\,\,\left[ {20{x^5} - 15{x^3} + 10{x^2}} \right]:\left[ {5{x^2}} \right] \cr & \,\,\,\,\, = {{20{x^5}} \over {5{x^2}}} - {{15{x^3}} \over {5{x^2}}} + {{10{x^2}} \over {5{x^2}}} \cr & \,\,\,\,\, = 4{x^3} - 3x + 2 \cr & b]\,\,\left[ {18{x^4}{y^5} + 24{x^3}{y^4} - 5{x^2}{y^3}} \right]:\left[ {6{x^2}{y^2}} \right] \cr & \,\,\,\,\, = {{18{x^4}{y^5}} \over {6{x^2}{y^2}}} + {{24{x^3}{y^4}} \over {6{x^2}{y^2}}} - {{5{x^2}{y^3}} \over {6{x^2}{y^2}}} \cr & \,\,\,\,\, = 3{x^2}{y^3} + 4x{y^2} - {5 \over 6}y \cr} \]