\[\eqalign{ & a]\,\,12{x^6}:3{x^3} = {{12{x^6}} \over {3{x^3}}} = {{12} \over 3}.{{{x^6}} \over {{x^3}}} = 4{x^{6 - 3}} = 4{x^3} \cr & b]\,\,21{x^8}{y^5}:\,\,\left[ {14{x^5}{y^3}} \right] = {{21{x^8}{y^5}} \over {14{x^5}{y^3}}} = {{21} \over {14}}.{{{x^8}} \over {{x^5}}}.{{{y^5}} \over {{y^3}}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {3 \over 2}{x^{8 - 5}}{y^{5 - 3}} = {3 \over 2}{x^3}{y^2} \cr & c]\,\,7{x^4}y:\,\,\left[ {2{x^3}} \right] = {{7{x^4}y} \over {2{x^3}}} = {7 \over 2}{{{x^4}} \over {{x^3}}}.y = {7 \over 2}xy \cr} \]
Đề bài
Thực hiện phép tính:
a] \[12{x^6}:3{x^3}\]
b] \[21{x^8}{y^5}:14{x^5}{y^3}\]
c] \[7{x^4}y:2{x^3}\] .
Lời giải chi tiết
\[\eqalign{ & a]\,\,12{x^6}:3{x^3} = {{12{x^6}} \over {3{x^3}}} = {{12} \over 3}.{{{x^6}} \over {{x^3}}} = 4{x^{6 - 3}} = 4{x^3} \cr & b]\,\,21{x^8}{y^5}:\,\,\left[ {14{x^5}{y^3}} \right] = {{21{x^8}{y^5}} \over {14{x^5}{y^3}}} = {{21} \over {14}}.{{{x^8}} \over {{x^5}}}.{{{y^5}} \over {{y^3}}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {3 \over 2}{x^{8 - 5}}{y^{5 - 3}} = {3 \over 2}{x^3}{y^2} \cr & c]\,\,7{x^4}y:\,\,\left[ {2{x^3}} \right] = {{7{x^4}y} \over {2{x^3}}} = {7 \over 2}{{{x^4}} \over {{x^3}}}.y = {7 \over 2}xy \cr} \]