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tử số = 2^10 . 3^8 - 2^10 . 3^9 = 2^10 . 3^8 . (1-3)
mẫu số = 2^10 . 3^8 + 3^8 . 2^10 . 5 = 2^10 . 3^8 . (1+5)
Đ/S: \(\frac{1-3}{1+5}\)=\(\frac{-1}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Tham khảo :
Câu hỏi của ๖ۣۜ๖ۣۜHσàηɠ ๖ۣۜTử ๖ۣۜGĭóッ - Toán lớp 7 - Học trực tuyến OLM
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 75 - 3.(2/13+1/17-1/19) 3.[25-(2/13+1/17-1/19)]
-------------------------------------- = ---------------------------------------------- = 3/11
275-11.(2/13+1/17-1/19) 11.[25-(2/13+1/17-1/19)]
a) \(\frac{75-\frac{6}{13}+\frac{3}{17}-\frac{3}{19}}{275-\frac{22}{13}+\frac{11}{17}-\frac{11}{19}}=\frac{75-3.\left(\frac{2}{13}+\frac{1}{17}-\frac{1}{19}\right)}{275-11.\left(\frac{2}{13}+\frac{1}{17}-\frac{1}{19}\right)}\)
\(=\frac{75-3}{275-11}\)
\(=\frac{72}{264}=\frac{3}{11}\)
b) \(\frac{2}{3.5}+\frac{7}{5.12}+\frac{9}{4.39}=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{12}+\frac{3}{52}\)
\(=\frac{1}{3}-\frac{1}{12}+\frac{3}{52}\)
\(=\frac{1}{4}+\frac{3}{52}=\frac{4}{13}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(C=\frac{2^{19}.3^9+5.2^{18}.3^9}{2^9.3^9.2^{10}+3^{10}.2^{20}}\)
\(C=\frac{3^9.\left(2^{19}+5.2^{18}\right)}{3^9.\left(2^9.2^{10}+3.2^{20}\right)}\)
\(C=\frac{2^{19}+5.2^{18}}{2^9.2^{10}+3.2^{20}}\)suy ra \(C=\frac{2^{18}.\left(2+5\right)}{2^{18}.\left(2+3.2^2\right)}\)
\(C=\frac{7}{14}\)
Vậy \(C=\frac{1}{2}\)
lm bt đc ko bn![leuleu leuleu](https://hoc24.vn/media/cke24/plugins/smiley/images/leuleu.png)
uk hahaha![haha haha](https://hoc24.vn/media/cke24/plugins/smiley/images/haha.png)