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Mình sửa lại để nha \(\left(125^7-625^5-25^9\right)\div99\)
Ta có \(\frac{\left(5^3\right)^7-\left(5^4\right)^6-\left(5^2\right)^9}{99}\)
\(=\frac{5^{21}-5^{20}-5^{18}}{99}\)
\(=\frac{5^{18}.\left(5^3-5^2-1\right)}{99}\)
\(=\frac{5^{18}.99}{99}\)
\(=5^{18}\)
\(\frac{\frac{1}{9}-\frac{1}{7}-\frac{1}{11}}{\frac{1}{9}-\frac{1}{7}-\frac{1}{11}}+\frac{\frac{3}{5}-\frac{3}{25}-\frac{3}{125}-\frac{3}{625}}{\frac{4}{5}-\frac{4}{25}-\frac{4}{125}-\frac{4}{625}}\)
= \(1+\frac{3.\left(\frac{1}{5}-\frac{1}{25}-\frac{1}{125}-\frac{1}{625}\right)}{4.\left(\frac{1}{5}-\frac{1}{25}-\frac{1}{125}-\frac{1}{625}\right)}\)
= \(1+\frac{3}{4}\)
= \(\frac{4}{4}+\frac{3}{4}\)
= \(\frac{7}{4}\)
HỌC TỐT
\(\frac{9^{14}\cdot25^5\cdot8^7}{18^{12}\cdot625^3\cdot24^3}=\frac{3^{28}\cdot5^{10}\cdot2^{21}}{2^{12}\cdot3^{24}\cdot5^{12}\cdot2^9\cdot3^3}=\frac{3\cdot3^{27}\cdot5^{10}\cdot2^{21}}{2^{21}\cdot3^{27}\cdot5^2\cdot5^{10}}=\frac{3}{5^2}=\frac{3}{25}\)
\(\frac{9^{14}.25^5.8^7}{18^{12}.625^3.24^3}\)
\(=\)\(\frac{3^{28}.5^{10}.2^{21}}{2^{12}.3^{24}.5^{12}.2^9.3^3}\)
\(=\)\(\frac{3.3^{27}.5^{10}.2^{21}}{2^{21}.3^{27}.5^2.5^{10}}\)
\(=\)\(\frac{3}{5^2}\)
\(=\)\(\frac{3}{25}\)
a) 25 . 84 = 25 . (23)4 = 25 . 212 = 217
b) 256 . 1253 = (52)6 . (53)3 = 512 . 59 = 521
c) 6255 : 257 = (252)5 : 257 = 2510 : 257 = 253
d) 123 . 33 = (12 . 3)3 = 363
6255.257 = (54)5.(52)7 = 520.514 = 534
6255.257=(54)5.(52)7=520.514=534