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HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023
a) Ta có:
\(\begin{array}{l}\frac{{ - 10}}{{18}} =\frac{{ - 10:2}}{{18:2}} = \frac{{ - 5}}{9};\,\,\,\\\frac{{10}}{{18}} = \frac{{10:2}}{{18:2}} =\frac{5}{9};\,\,\\\,\frac{{15}}{{ - 27}} =\frac{{15:(-3)}}{{ - 27:(-3)}} = \frac{{ - 5}}{9};\,\\ - \frac{{20}}{{36}} =- \frac{{20:4}}{{36:4}}= \frac{{ - 5}}{9}.\end{array}\)
Vậy những phân số nào biểu diễn số hữu tỉ \(\frac{{ - 5}}{9}\) là: \(\frac{{ - 10}}{{18}};\,\frac{{15}}{{ - 27}};\, - \frac{{20}}{{36}}.\)
b) Số đối của các số \(12;\,\frac{{ 4}}{9};\, - 0,375;\,\frac{0}{5};\,-2\frac{2}{5}\) lần lượt là: \( - 12;\,\frac{-4}{9};\,0,375;\,\frac{0}{5};\, 2\frac{2}{5}\).
NY
2
6 tháng 10 2015
\(\frac{15^{20}\cdot9^{10}}{27^{12}\cdot25^{10}}=\frac{3^{20}\cdot5^{20}\cdot3^{20}}{3^{36}\cdot5^{20}}=\frac{3^{40}}{3^{36}}=3^4=81\)
6 tháng 10 2015
\(=\frac{3^{20}.5^{20}.3^{20}}{3^{36}.5^{20}}=\frac{3^{40}}{3^{36}}=3^4=81\)
T
0
4 tháng 1 2022
\(\dfrac{45^{10}\cdot5^{20}}{75^{15}}=\dfrac{\left(3^2\cdot5\right)^{10}\cdot5^{20}}{\left(3\cdot5^2\right)^{15}}=\dfrac{3^{20}\cdot5^{10}\cdot5^{20}}{3^{15}\cdot5^{30}}=3^5=243\\ \dfrac{6^6+6^3+3^3+3^6}{-73}=\dfrac{46656+216+27+729}{-73}=-\dfrac{47628}{73}\\ \dfrac{27^7+3^{15}}{9^9-27}=\dfrac{\left(3^3\right)^7+3^{15}}{\left(3^2\right)^9-3^3}=\dfrac{3^{21}+3^{15}}{3^{18}-3^3}=\dfrac{3^{15}\left(3^6+1\right)}{3^3\left(3^{15}-1\right)}=\dfrac{3^5\cdot730}{3^{15}-1}\\ \dfrac{8^{20}+4^{20}}{4^{25}+64^5}=\dfrac{\left(2^3\right)^{20}+\left(2^2\right)^{20}}{\left(2^2\right)^{25}+\left(2^6\right)^5}=\dfrac{2^{60}+2^{40}}{2^{50}+2^{30}}=\dfrac{2^{40}\left(2^{20}+1\right)}{2^{30}\left(2^{20}+1\right)}=2^{10}=1024\)
BT
1
18 tháng 5 2018
ta có : (ghi lại đề)
=6+12+18+24+30/3+6+9+12+15
=2*(3/3+6/6+9/9+12/12+15/15)
=2*(1+1+1+1+1)
=2*5=10
chúc main học tốt nhé
5 tháng 10 2016
\(A=\frac{81^4.3^{10}.27^5:3^{12}}{3^{18}:9^3.243^2}=\frac{3^{16}.3^{10}.3^{15}:3^{12}}{3^{18}:3^6.3^{10}}=\frac{3^{29}}{3^{22}}=3^7\)
\(B=\frac{2.55^2-9.55^{21}}{25^{10}}:\frac{5\left(3.7^{15}-19.7^{14}\right)}{7^{16}+3.7^{15}}=\frac{2.55^2-9.55^2.55^{19}}{25^{10}}:\frac{5\left(21.7^{14}-19.7^{14}\right)}{7.7^{15}+3.7^{15}}=\frac{55^2\left(55^{19}.9-2\right)}{25^{10}}:\frac{5.7^{14}.2}{7^{15}.10}=\frac{55^2\left(55^{19}.9-2\right)}{25^{10}}.\frac{7^{15}.10}{5.7^{14}.2}\)Chịu ==
MM
2
13 tháng 7 2017
f) \(\frac{25^2.20^4}{5^{10}.4^5}=\frac{\left(5^2\right)^5.\left(4.5\right)^4}{5^{10}.4^5}=\frac{5^{10}.5^4.4^4}{5^{10}.4^5}=\frac{5^{14}.4^4}{5^{10}.4^5}=\frac{5^4}{4}\)
i) \(\frac{9^{15}.81^4}{27^8.3^{20}}=\frac{\left(3^2\right)^{15}.\left(3^4\right)^4}{\left(3^3\right)^8.3^{20}}=\frac{3^{30}.3^{16}}{3^{24}.3^{20}}=\frac{3^{46}}{3^{44}}=3^2=9\)
13 tháng 7 2017
f) Ta có: \(\frac{25^2.20^4}{5^{10}.4^5}\)= \(\frac{\left(5^2\right)^2.\left(4.5\right)^4}{5^{10}.4^5}\)= \(\frac{5^4.4^4.5^4}{5^{10}.4^5}\)= \(\frac{5^8.4^4}{5^{10}.4^5}\)= \(\frac{1}{5^2.4}\)=\(\frac{1}{100}\).
i) Ta có: \(\frac{9^{15}.81^4}{27^8.3^{20}}\)= \(\frac{\left(3^2\right)^{15}.\left(3^4\right)^4}{\left(3^3\right)^8.3^{20}}\)= \(\frac{3^{30}.3^8}{3^{24}.3^{20}}\)= \(\frac{3^{38}}{3^{44}}\)=\(\frac{1}{3^6}\)= \(\frac{1}{729}\)
17 tháng 10 2018
=\(\frac{2^{30}3^{16}.5^{50}.7+2^{30}.3^{15}.3^2.11.5^{48}}{11.2^{25}.2^4.5^4.3^{18}.5^{18}.5^{30}-2^{30}.5^{30}.5^{22}.3^{18}}\)
=\(\frac{2^{30}.3^{16}.5^{50}.7+2^{30}.3^{17}.11.5^{48}}{11.2^{29}.5^{52}.3^{18}-2^{30}.5^{52}.3^{18}}\)
=\(\frac{2^{30}.3^{16}.5^{48}.11\left(5^2.7+3\right)}{2^{29}.5^{52}.3^{18}.11\left(1-2\right)}\)
=\(\frac{2.\left(5^2.7+3\right)}{5^4.3^2\left(1-2\right)}\)
=\(\frac{2.178}{5^4.3^2.\left(-1\right)}\)
=\(\frac{356}{-5625}\)
Hk tốt
HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023
\(\frac{{12}}{{25}} = 0,48;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{27}}{2} = 13,5;\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{10}}{9} = 1,(1)\)
\(\frac{15^{20}.9^{10}}{27^{12}.25^{10}}=\frac{\left(3.5\right)^{20}.\left(3^2\right)^{10}}{\left(3^3\right)^{12}.\left(5^2\right)^{10}}=\frac{3^{20}.5^{20}.3^{20}}{3^{36}.5^{20}}=3^4=81\)