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Có : 10A = 10.(10^11-1)/10^12-1 = 10^12-10/10^12-1
Vì : 0 < 10^12-10 < 10^12-1 => 10A < 1 (1)
10B = 10.(10^10+1)/10^11+1 = 10^11+10/10^11+1
Vì : 10^11+10 > 10^11+1 > 0 => 10B > 1 (2)
Từ (1) và (2) => 10A < 10B
=> A < B
Tk mk nha
\(A=\frac{10^{11}-1}{10^{12}-1}\)
\(B=\frac{10^{10}+1}{10^{11}+1}\)
Mà \(\frac{10^{11}-1}{10^{12}-1}< 1\); \(\frac{10^{10}+1}{10^{11}+1}< 1\)
\(\Rightarrow\)\(A,B< 1\)
Ta có:
\(10^{11}-1>10^{10}+1\); \(10^{12}-1>10^{11}+1\)
\(\Rightarrow A>B\)
Vậy A > B
ta có :
\(25^{1008}=\left(5^2\right)^{1008}=5^{2.1008}=5^{2016}\)
mà \(5^{2017}>5^{2016}\)
\(\Rightarrow\)\(5^{2017}>\left(5^2\right)^{1008}\)
\(\Rightarrow\)\(5^{2017}>25^{1008}\)
có \(5^{2017}=\left(5^2\right)^{1008}\times5\)\(=25^{1008}\times5\)
mà \(=25^{1008}\times5\)> \(25^{1008}\)
nên \(5^{2017}>25^{1008}\)
Ta có :
`3,09 xx 10^9`
`=3,09 xx 10 xx 10^8`
`= 30,9 xx 10^8`
Mà `30,9 > 8,27`
Vậy `8,27 xx 10^8 < 3,09 xx 10^9`
Ta có : 3 , 09 × 10 9 = 3 , 09 × 10 × 10 8 = 30 , 9 × 10 8 Mà 30 , 9 > 8 , 27 Vậy 8 , 27 × 10 8 < 3 , 09 × 10 9
\(\left(\dfrac{1}{10}\right)^{15}=\left[\left(\dfrac{1}{10}\right)^3\right]^5=\left(\dfrac{1}{1000}\right)^5=\left(\dfrac{10}{10000}\right)^5\)
\(\left(\dfrac{3}{10}\right)^{20}=\left[\left(\dfrac{3}{10}\right)^4\right]^5=\left(\dfrac{81}{10000}\right)^5\)
\(\dfrac{10}{10000}< \dfrac{81}{10000}\)
\(\Rightarrow\left(\dfrac{10}{10000}\right)^5< \left(\dfrac{81}{10000}\right)^5\)
\(\Rightarrow\left(\dfrac{1}{10}\right)^{15}< \left(\dfrac{3}{10}\right)^{20}\)
Ta có:
\(\left(\dfrac{1}{10}\right)^{15}=\left[\left(\dfrac{1}{10}\right)^3\right]^5=\left(\dfrac{1}{1000}\right)^5\)
\(\left(\dfrac{3}{10}\right)^{20}=\left[\left(\dfrac{3}{10}\right)^4\right]^5=\left(\dfrac{81}{10000}\right)^5\)
Ta thấy: \(\dfrac{1}{1000}< \dfrac{81}{10000}\)
\(\Rightarrow\left(\dfrac{1}{1000}\right)^5< \left(\dfrac{81}{10000}\right)^5\)
\(\Rightarrow\left(\dfrac{1}{10}\right)^{15}< \left(\dfrac{3}{10}\right)^{20}\)
\(10\cdot\dfrac{10^3+5}{10^4+5}=\dfrac{10^4+5+45}{10^4+5}=1+\dfrac{45}{10^4+5}\)
\(10\cdot\dfrac{10^2+5}{10^3+5}=\dfrac{10^3+5+45}{10^3+5}=1+\dfrac{45}{10^3+5}\)
mà \(\dfrac{45}{10^4+5}< \dfrac{45}{10^3+5}\)
nên \(\dfrac{10^3+5}{10^4+5}< \dfrac{10^2+5}{10^3+5}\)
Ta có :
1990^10 + 1990^9 = 1990.1990^9 + 1990^9 = 1991^9 < 1991^10
=> (1990^10 + 1990^9) < 1991^10
Ta có :
\(A=\dfrac{10^{11}-1}{10^{12}-1}< 1\)
\(\Leftrightarrow A< \dfrac{10^{11}-1+11}{10^{12}-1+11}=\dfrac{10^{11}+10}{10^{12}+10}=\dfrac{10\left(10^{10}+1\right)}{10\left(10^{11}+1\right)}=\dfrac{10^{10}+1}{10^{11}+1}=B\)
Vậy \(\dfrac{10^{11}-1}{10^{12}-1}< \dfrac{10^{10}+1}{10^{11}+1}\)
Vậy...
96142 < 10 * 2393