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0 nha em
trong các cặp đó nó sẽ tồn tại cặp 1000-10^3 suy ra 10^3 -10^3 = 0 suy ra tích đó = 0
\(x^2+\left(y-\dfrac{1}{10}\right)^{2018}=0\\ \Leftrightarrow x^2+\left[\left(y-\dfrac{1}{10}\right)^{1009}\right]^2=0\\ \Leftrightarrow\left[{}\begin{matrix}x^2=0\\\left(y-\dfrac{1}{10}\right)^{1009}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\y=\dfrac{1}{10}\end{matrix}\right.\)
Vì 103 = 1000 nên :
( 1000 - 103 ) = 0
Số nào nhân với 0 cũng bằng 0
Vậy A = 0
Vì trong dãy trên sẽ có 1000-10\(^3\)=0
\(\Rightarrow\)(1000-1)(1000-2\(^3\))...(1000-50\(^3\))=0
Tính: (1000−13).(1000−23).(1000−33)......(1000−503)=..........
Ta có : 1000 - 13 = 1000 - 1000 = 0
Nên : (1000−13).(1000−23).(1000−33)......(1000−503)= 0
Vậy ...
\(\left(1000-1^3\right).\left(1000-2^3\right).\left(1000-3^3\right)....\left(1000-50^3\right)\)
\(=\left(1000-1^3\right).\left(1000-2^3\right)...\left(1000-10^3\right)....\left(1000-50^3\right)\)
\(=\left(1000-1^3\right).\left(1000-2^3\right)...\left(1000-1000\right)....\left(1000-50^3\right)\)
\(=\left(1000-1^3\right).\left(1000-2^3\right)...0...\left(1000-50^3\right)\)
\(=0\)
a, Ta có :\(A=\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{49}}+\dfrac{1}{2^{50}}\\ \Rightarrow2A=1+\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{49}}\\ \Rightarrow2A-A=\left(1+\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{49}}\right)-\left(\dfrac{1}{2^1}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{50}}\right)\\ \Rightarrow A=1-\dfrac{1}{2^{50}}< 1\\ \Rightarrow A< 1\) Vậy \(A< 1\)
b, Ta có :
\(B=\dfrac{1}{3^1}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{100}}\\ \Rightarrow3B=1+\dfrac{1}{3^1}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{99}}\\ \Rightarrow3B-B=\left(1+\dfrac{1}{3^1}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{99}}\right)-\left(\dfrac{1}{3^1}+\dfrac{1}{3^2}+...+\dfrac{1}{3^{100}}\right)\\ \Rightarrow2B=1-\dfrac{1}{3^{100}}< 1\\ \Rightarrow B< \dfrac{1}{2}\)Vậy \(B< \dfrac{1}{2}\)
c, Ta có :
\(C=\dfrac{1}{4^1}+\dfrac{1}{4^2}+...+\dfrac{1}{4^{1000}}\\ \Rightarrow4C=1+\dfrac{1}{4^1}+\dfrac{1}{4^2}+...+\dfrac{1}{4^{999}}\\\Rightarrow4C-C=\left(1+\dfrac{1}{4^1}+\dfrac{1}{4^2}+...+\dfrac{1}{4^{999}}\right)-\left(\dfrac{1}{4^1}+\dfrac{1}{4^2}+...+\dfrac{1}{4^{1000}}\right)\\ \Rightarrow3C=1-\dfrac{1}{4^{1000}}< 1\\ \Rightarrow C< \dfrac{1}{3}\)Vậy \(C< \dfrac{1}{3}\)
a: \(=\dfrac{1}{50}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{49}-\dfrac{1}{50}\right)\)
\(=\dfrac{1}{5}-\dfrac{49}{50}=\dfrac{-48}{50}=-\dfrac{24}{25}\)
501−(1−21+21−31+...+491−501)
=15−4950=−4850=−2425=51−5049=50−48=−2524