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HK
1
NP
4
9 tháng 12 2016
1/10+2/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10+55/10
=1+2+3+4+5+6+7+8+9+55 /10
=100/10
=10
DT
0
HT
16 tháng 3 2022
\(e.\dfrac{7}{10}\cdot\dfrac{-3}{5}+\dfrac{7}{10}\cdot\dfrac{-2}{5}-\dfrac{3}{10}\)
\(=\dfrac{7}{10}\cdot\left[\left(\dfrac{-3}{5}\right)+\left(\dfrac{-2}{5}\right)\right]-\dfrac{3}{10}\)
\(=\dfrac{7}{10}\cdot1-\dfrac{3}{10}=\dfrac{4}{10}=\dfrac{2}{5}\)
\(f.\dfrac{-3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+2\dfrac{3}{7}\)
\(=\dfrac{-3}{7}\cdot\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{17}{3}\)
\(=\dfrac{-3}{7}\cdot1+\dfrac{17}{3}=\dfrac{-9}{21}+\dfrac{119}{21}=\dfrac{110}{21}\)
\(g.\dfrac{5}{9}\cdot\dfrac{10}{17}+\dfrac{5}{9}\cdot\dfrac{9}{17}-\dfrac{5}{9}\cdot\dfrac{2}{17}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{10}{17}+\dfrac{9}{17}-\dfrac{2}{17}\right)\)
\(=\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)
N
0
16 tháng 3 2017
ta có : \(\frac{10^9+2}{10^9-1}=\frac{10^9}{10^9-3}\)
\(\Leftrightarrow\left(10^9+2\right)\left(10^9-3\right)=\left(10^9-1\right)10^9\)
\(\Leftrightarrow10^{18}-10^9.3+2.10^9-6=10^{18}-10^9\)
\(\Rightarrow10^{18}-10^9.3+2.10^9-6=10^{18}-\left(10^9.3-2.10^9+6\right)\)
\(=10^{18}-\left(10^9+6\right)\)
vì \(-10^9>-\left(10^9+6\right)\Rightarrow10^{18}-10^9>10^{18}-\left(10^9+6\right)\)
\(\Rightarrow A>B\)
FT
16 tháng 3 2017
Ta có: A=\(\frac{10^9+2}{10^9-1}=\frac{10^9-1+3}{10^9-1}=1+\frac{3}{10^9-1}\)
B=\(\frac{10^9}{10^9-3}=\frac{10^9-3+3}{10^9-3}=1+\frac{3}{10^9-3}\)
Mà \(\frac{3}{10^9-1}< \frac{3}{10^9-3}\Rightarrow1+\frac{3}{10^9-1}< 1+\frac{3}{10^9-3}\Rightarrow A< B\)
Vậy A<B
VN
Võ Ngọc Phương
VIP
20 tháng 1
\(\dfrac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\dfrac{2^{10}.3^9\left(3-1\right)}{2^9.3^{10}}=\dfrac{2^{10}.3^9.2}{2^9.3^{10}}=\dfrac{2^9.2.3^9.2}{2^9.3.3^9}=\dfrac{4}{3}\)
VN
Võ Ngọc Phương
VIP
20 tháng 1
\(\dfrac{2^{10}.3^{10}-2^{10}.3^9}{2^9.3^{10}}=\dfrac{2^{10}.3^9\left(3-1\right)}{2^9.3^{10}}=\dfrac{2^{10}.3^9.2}{2^9.3^{10}}=\dfrac{2^{10}.2.3^9.2}{2^9.3.3^9}=\dfrac{4}{3}\)
TQ
3
20 tháng 6 2015
9 + 10 + 9 + 10 +9 +10 + 9 +10 + M + C + M
= 9 + 10 + 9 + 10 +9 +10 + 9 +10 + 1000 + 100 + 1000
= 2176
20 tháng 6 2015
9 + 10 + 9 + 10 +9 +10 + 9 +10 + M + C + M
= 9 + 10 + 9 + 10 +9 +10 + 9 +10 + 1000 + 100 + 1000
9 x 4+ 10 x 4 + 1000 x 2 +100
= 2176
`Answer:`
Đặt \(N=\frac{9}{10}+\frac{9}{10^2}+\frac{9}{10^3}+...+\frac{9}{10^{10}}\)
\(\Rightarrow\frac{N}{9}=\frac{1}{10}+\frac{1}{10^2}+\frac{1}{10^3}+...+\frac{1}{10^{10}}\)
Ta có \(\frac{N}{90}=\frac{1}{10^2}+\frac{1}{10^3}+\frac{1}{10^4}+...+\frac{1}{10^{11}}\)
\(\Rightarrow\frac{N}{9}-\frac{N}{90}=\left(\frac{1}{10}+\frac{1}{10^2}+\frac{1}{10^3}+...+\frac{1}{10^{10}}\right)-\left(\frac{1}{10^2}+\frac{1}{10^3}+\frac{1}{10^4}+...+\frac{1}{10^{11}}\right)\)
\(\Rightarrow\frac{10N}{90}-\frac{N}{90}=\frac{1}{10}+\frac{1}{10^2}+\frac{1}{10^3}+...+\frac{1}{10^{10}}-\frac{1}{10^2}-\frac{1}{10^3}-\frac{1}{10^4}-...-\frac{1}{10^{11}}\)
\(\Rightarrow\frac{9N}{90}=\frac{1}{10}-\frac{1}{10^{11}}\)
\(\Rightarrow\frac{N}{10}=\frac{10^{10}-1}{10^{11}}\)
\(\Rightarrow N=\frac{10^{10}-1}{10^{10}}\)