a: \(=\dfrac{-39+19+10}{12}=\dfrac{-10}{12}=\dfrac{-5}{6}\)

b: \(=\dfrac{2^{30}\cdot3^{16}\cdot7-2^{34}\cdot3^{15}}{2^{28}\cdot3^{21}-2^{28}\cdot3^{17}}\)

\(=\dfrac{2^{30}\cdot3^{15}\left(3\cdot7-2^4\right)}{2^{28}\cdot3^{17}\left(3^4-1\right)}=\dfrac{2^2}{3^2}\cdot\dfrac{21-16}{80}=\dfrac{4}{9}\cdot\dfrac{5}{80}\)

\(=\dfrac{20}{720}=\dfrac{1}{36}\)

\(B=\frac{7.6^{10}.2^{20}.3^6-2^{19}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}\)

\(B=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{19}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-2^2.3^{17}.2^{26}}\)

\(B=\frac{7.2^{30}.3^{16}-2^{34}.3^{15}}{3^{21}.2^{11}-2^{28}.3^{17}}\)

\(B=\frac{2^{30}.3^{15}.\left(7.3-2^4\right)}{3^{17}.2^{11}.\left(3^4-2^{17}\right)}\)

\(B=\frac{2^{19}.\left(21-2^4\right)}{3^2.\left(3^4-2^{17}\right)}\)

@_@ tự tính!

\(B=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{19}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-4.3^{17}.2^{26}}\\ B=\frac{7.2^{10}.3^{10}.2^{20}.3^6-2^{19}.2^{15}.3^{15}}{3^2.2^{19}.3^{19}.2^9-2^2.3^{17}.2^{26}}\\ B=\frac{7.2^{30}.3^{16}-2^{34}.3^{15}}{3^{21}.2^{28}-2^{28}.3^{17}}\)   

\(B=\frac{7.2^{30}.3.3^{15}-2^{34}.3^{15}}{3^{15}.3^6.2^{28}-2^{28}.3^{15}.3^2}\\ B=\frac{3^{15}.\left(7.2^{30}.3-3^{34}\right)}{3^{15}.\cdot\left(3^6-3^2\right)}\\ B=\frac{7.2^{30}.3-3^{34}}{3^6-3^2}\)

\(A=\frac{7.6^{10}.2^{20}.3^6-2^{18}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}=\frac{7.\left(2.3\right)^{10}.2^{20}.3^6-2^{18}.\left(2.3\right)^{15}}{3^2.\left(2.3\right)^{19}.2^9-2^2.3^{17}.2^{26}}\)

                                                        \(=\frac{7.2^{10}.3^{10}.2^{20}.3^6-2^{18}.2^{15}.3^{15}}{3^2.2^{19}.3^{19}.2^9-2^2.3^{17}.2^{26}}\)

                                                         \(=\frac{7.2^{30}.3^{16}-2^{33}.3^{15}}{2^{28}.3^{21}-2^{28}.3^{17}}\)

                                                             \(=\frac{2^{30}.3^{15}.\left(7.3-2^3\right)}{2^{28}.3^{17}.\left(3^4-1\right)}\)

                                                              \(=\frac{2^2.13}{3^2.80}=\frac{4.13}{9.80}=\frac{13}{180}\)

\(A=\frac{7\cdot2^{10}\cdot3^{10}\cdot2^{20}\cdot3^6-2^{18}\cdot2^{15}\cdot3^{15}}{3^2\cdot3^{19}\cdot2^{19}\cdot2^9-2^2\cdot3^{17}\cdot2^{26}}=\frac{7\cdot2^{30}\cdot3^{16}-2^{33}\cdot3^{15}}{3^{21}\cdot2^{28}-2^{28}\cdot3^{17}}\)

\(A=\frac{2^{30}\cdot3^{15}\left(7\cdot3-2^3\right)}{2^{28}\cdot3^{17}\left(3^4-1\right)}=\frac{2^{30}\cdot3^{15}\cdot13}{2^{28}\cdot3^{17}\cdot2^4\cdot5}=\frac{13}{2^2\cdot3^2\cdot5}=\frac{13}{180}\)

Chị ko bt có sai ko nx nếu có sai thông cảm chị nha

^-^

mai mik phải nộp rồi ạ   

Bài làm:

Ta có: \(\frac{7.6^{10}.2^{20}.3^6-2^{19}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}\)

\(=\frac{7.2^{10}.3^{10}.2^{20}.3^6-2^{19}.2^{15}.3^{15}}{3^2.2^{19}.3^{19}.2^9-2^2.3^{17}.2^{26}}\)

\(=\frac{2^{30}.3^{16}.7-2^{34}.3^{15}}{2^{28}.3^{21}-2^{28}.3^{17}}\)

\(=\frac{2^{30}.3^{15}\left(3.7-2^4\right)}{2^{28}.3^{17}\left(3^4-1\right)}\)

\(=\frac{2^2\left(21-16\right)}{3^2\left(81-1\right)}\)

\(=\frac{2^2.5}{3^2.80}\)

\(=\frac{1}{36}\)

\(=\frac{7.6^{11}.2^{19}.3^5-2^{19}.6^{15}}{3^{21}.2^{28}-3^{17}.2^{28}}=\frac{2^{19}.6^{11}.\left(7.3^5-6^4\right)}{3^{17}.2^{28}.\left(3^4-1\right)}=\frac{2^{30}.3^{11}.3^4.\left(7.3-2^4\right)}{3^{17}.2^{28}.\left(3^4-1\right)}=\frac{2^2.13}{3^2.80}=\frac{13}{9.20}=\frac{13}{180}\)

phải ra là 1/36 bạn làm nhầm bước 2^2.5/3^2.80=1/36

\(B=\frac{7.6^{10}.2^{20}.3^6-2^{19}.6^{15}}{9.6^{19}.2^9-4.3^{17}.2^{26}}\)

\(B=\frac{7.3^{16}.2^{30}-2^{34}.3^{15}}{3^{21}.2^{28}-2^{28}.3^{17}}\)

\(=\frac{3^{15}.2^{30}.\left(7.3-2^4\right)}{3^{17}.2^{28}.\left(3^4-1\right)}=\frac{2^2.\left(21-16\right)}{3^2.\left(81-1\right)}=\frac{2^2.5}{3^2.2^4.5}=\frac{1}{3^2.2^2}=\frac{1}{36}\)