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7 tháng 8 2016
1 Tinh
89/16+25(9/16÷125/64)÷(-27/8)
= \(\frac{89}{16}+25\left(\frac{9}{16}:\frac{125}{64}\right):-\frac{27}{8}\)
=\(\frac{89}{16}+\frac{25.36}{125}:-\frac{27}{8}\)
=\(\frac{89}{16}-\frac{32}{15}=\frac{823}{240}\)
7 tháng 8 2016
\(\frac{89}{16}+25.\left(\frac{9}{16}:\frac{125}{64}\right):\left(\frac{-27}{8}\right)\)
=\(\frac{89}{16}+25.\frac{36}{125}:\left(\frac{-27}{8}\right)\)
=\(\frac{89}{16}+\frac{36}{5}:\left(\frac{-27}{8}\right)\)
=\(\frac{89}{16}+\left(\frac{-32}{15}\right)\)
=\(\frac{823}{240}\)
MC
2
HD
24 tháng 9 2017
\(4\dfrac{25}{16}+25\left(\dfrac{9}{16}:\dfrac{125}{64}:\dfrac{-27}{8}\right)\)
\(=\dfrac{89}{16}+25\left(\dfrac{36}{125}:\dfrac{-27}{8}\right)\)
\(=\dfrac{89}{16}+25.\dfrac{-32}{375}\)
\(=\dfrac{89}{16}+\dfrac{-32}{15}=\dfrac{823}{240}\)
Chúc bạn học tốt!
L
24 tháng 9 2017
\(4\dfrac{25}{16}+25\left(\dfrac{9}{16}:\dfrac{125}{64}:-\dfrac{27}{8}\right)\)
= \(\dfrac{89}{16}+25\left(\dfrac{9}{16}.\dfrac{64}{125}:-\dfrac{27}{8}\right)\)
= \(\dfrac{89}{16}+25\left(\dfrac{36}{125}:-\dfrac{27}{8}\right)\)
= \(\dfrac{89}{16}+25\left(\dfrac{36}{125}.-\dfrac{8}{27}\right)\)
= \(\dfrac{89}{16}+25.-\dfrac{32}{375}\)
\(=\dfrac{89}{16}+-\dfrac{32}{15}\)
= \(\dfrac{823}{240}\)
XT
0
BC
31 tháng 3 2019
a)Ta có:
\(A=4\frac{25}{16}+25\left(\frac{9}{16}:\frac{125}{64}\right):\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+25.\frac{36}{125}:\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+\frac{36}{5}:\frac{-27}{8}\)
\(\Rightarrow A=\frac{89}{16}+\frac{-32}{15}\)
\(\Rightarrow A=\frac{823}{240}\)
Vậy A=.....
b)Ta có:
\(C=\frac{2^3}{3.5}+\frac{2^3}{5.7}+\frac{2^3}{7.9}+...+\frac{2^3}{101.103}\)
\(\Rightarrow C=\frac{2^2.2}{3.5}+\frac{2^2.2}{5.7}+\frac{2^2.2}{7.9}+...+\frac{2^2.2}{101.103}\)
\(\Rightarrow C=2^2\left(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{101.103}\right)\)
\(\Rightarrow C=4\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+....+\frac{1}{101}-\frac{1}{103}\right)\)
\(\Rightarrow C=4\left(\frac{1}{3}-\frac{1}{103}\right)\)
\(\Rightarrow C=4.\frac{100}{309}\)
\(\Rightarrow C=\frac{400}{309}\)
Vậy C=.....
TG
3 tháng 8 2020
1) \(125^5:25^7\)
\(=\left(5^3\right)^5:\left(5^2\right)^7\)
\(=5^{15}:5^{14}\)
= 5
2) \(27^8:9^9\)
\(=\left(3^3\right)^8:\left(3^2\right)^9\)
\(=3^{24}:3^{18}\)
\(=3^6\)
3) \(36^5:6^8\)
\(=\left(6^2\right)^5:6^8\)
\(=6^{10}:6^8\)
\(=6^2\)
4) \(49^6:7^{10}\)
\(=\left(7^2\right)^6:7^{10}\)
\(=7^{12}:7^{10}=7^2\)
5) \(7^{20}:49^9\)
\(=7^{20}:\left(7^2\right)^9\)
\(=7^{20}:7^{18}=7^2\)
6) \(\frac{1}{2^{10}}:\frac{1}{8^3}\)
\(=\frac{1}{2^{10}}:\frac{1}{\left(2^3\right)^3}\)
\(=\frac{1}{2^{10}}:\frac{1}{2^9}=\frac{1}{2^{10}}.\frac{2^9}{1}=\frac{1}{2}\)
7) \(\left(-\frac{1}{2}\right)^{21}:\frac{1}{4^{10}}\)
\(=\frac{\left(-1\right)^{21}}{2^{21}}:\frac{1}{\left(2^2\right)^{10}}\)
\(=-\frac{1}{2^{21}}:\frac{1}{2^{20}}=-\frac{1}{2^{21}}.\frac{2^{20}}{1}\)
\(=-\frac{1}{2}\)
8) \(\frac{1}{16^5}:\left(-\frac{1}{2}\right)^{18}\)
\(=\frac{1}{\left(2^4\right)^5}:\frac{\left(-1\right)^{18}}{2^{18}}\)
\(=\frac{1}{2^{20}}:\frac{1}{2^{18}}\)
\(=\frac{1}{2^{20}}.\frac{2^{18}}{1}=\frac{1}{4}\)
9) \(\frac{1}{5^{30}}:\frac{1}{25^{14}}\)
\(=\frac{1}{5^{30}}:\frac{1}{\left(5^2\right)^{14}}\)
\(=\frac{1}{5^{30}}:\frac{1}{5^{28}}=\frac{1}{25}\)
24 tháng 9 2020
\(9^7+81^4-27^5\)
\(=\left(3^2\right)^7+\left(3^4\right)^4-\left(3^3\right)^5\)
\(=3^{14}+3^{16}-3^{15}\)
\(=3^{14}.\left(1+3^2-3\right)\)
\(=3^{14}.7⋮7\)
=> đpcm
\(25^{25}+5^{49}-125^{16}\)
\(=\left(5^2\right)^{25}+5^{49}-\left(5^3\right)^{16}\)
\(=5^{50}+5^{49}-5^{48}\)
\(=5^{48}.\left(5^2+5-1\right)\)
\(=5^{48}.29⋮29\)
=> đpcm
B
24 tháng 9 2020
Bài làm :
\(\text{1) }9^7+81^4-27^5\)
\(=\left(3^2\right)^7+\left(3^4\right)^4-\left(3^3\right)^5\)
\(=3^{14}+3^{16}-3^{15}\)
\(=3^{14}\left(1+3^2-3\right)\)
\(=3^{14}.7⋮7\)
=> Điều phải chứng minh
\(\text{2)}25^{25}+5^{49}-125^{16}\)
\(=\left(5^2\right)^{25}+5^{49}-\left(5^3\right)^{16}\)
\(=5^{50}+5^{49}-5^{48}\)
\(=5^{48}\left(5^2+5-1\right)\)
\(=5^{48}.29⋮29\)
=> Điều phải chứng minh
\(\frac{25}{4}+\frac{225}{16}:\frac{-3375}{512}\)
\(\frac{25}{4}+\frac{-32}{15}\)
\(=\frac{247}{60}\)
\(\frac{25}{4}+25\times\frac{9}{16}:\left[\frac{125}{64}\times\left(\frac{-27}{8}\right)\right].\)
\(=\frac{25}{4}+25\times\frac{9}{16}:\frac{-3375}{512}\)
\(=\frac{25}{4}+\frac{225}{16}:\frac{-3375}{512}\)
\(=\frac{25}{4}+\frac{-32}{15}\)
\(=\frac{247}{60}\)