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

\(\eqalign{  & a)\,\,12{x^6}:3{x^3} = {{12{x^6}} \over {3{x^3}}} = {{12} \over 3}.{{{x^6}} \over {{x^3}}} = 4{x^{6 - 3}} = 4{x^3}  \cr  & b)\,\,21{x^8}{y^5}:\,\,\left( {14{x^5}{y^3}} \right) = {{21{x^8}{y^5}} \over {14{x^5}{y^3}}} = {{21} \over {14}}.{{{x^8}} \over {{x^5}}}.{{{y^5}} \over {{y^3}}}  \cr  & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {3 \over 2}{x^{8 - 5}}{y^{5 - 3}} = {3 \over 2}{x^3}{y^2}  \cr  & c)\,\,7{x^4}y:\,\,\left( {2{x^3}} \right) = {{7{x^4}y} \over {2{x^3}}} = {7 \over 2}{{{x^4}} \over {{x^3}}}.y = {7 \over 2}xy \cr} \)

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