So sánh:
\(x=\frac{357}{-352}\)và \(y=\frac{-1000}{999}\)
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Ta so sánh hai phân số \(\frac{2010}{2011}\)và \(\frac{1000}{999}\)có :
\(\frac{2010}{2011}< \frac{1000}{999}\)
\(\Rightarrow\left(\frac{-2010}{2011}\right)>\left(\frac{-1000}{999}\right)\)
Vậy ...
1 - \(\frac{999}{556}\) = \(\frac{-443}{556}\)
1 - \(\frac{1000}{557}\) = \(\frac{-443}{557}\)
Vì \(\frac{-443}{556}\) < \(\frac{-443}{557}\) nên \(\frac{999}{556}\) > \(\frac{1000}{557}\)
First we have :
\(\frac{999}{556}=\frac{999\cdot557}{556\cdot557}\)
Then : \(999\cdot557=999\cdot556+999\)
Next we have : \(1000\cdot556=999\cdot556+556\)
As you see : \(999\cdot556+556< 999\cdot556+999\)
So :\(\frac{999}{556}< \frac{1000}{557}\)
Ta có :
\(C=\frac{1}{4}+\frac{1}{4^2}+.....+\frac{1}{4^{1000}}\)
\(\Rightarrow4C=1+\frac{1}{4}+.....+\frac{1}{4^{1999}}\)
\(\Rightarrow4C-C=\left(1+\frac{1}{4}+.....+\frac{1}{4^{1999}}\right)-\left(\frac{1}{4}+\frac{1}{4^2}+.....+\frac{1}{4^{1000}}\right)\)
\(\Rightarrow3C=1-\frac{1}{4^{1000}}\)
\(\Rightarrow C=\frac{1}{3}-\frac{1}{3.4^{1000}}< \frac{1}{3}\)
=> C < 1 / 3
Ta có:
\(C=\frac{1}{4}+\frac{1}{4^2}+...+\frac{1}{4^{1000}}\)
\(\Rightarrow4C=1+\frac{1}{4}+...+\frac{1}{4^{999}}\)
\(\Rightarrow4C-C=\left(1+\frac{1}{4}+\frac{1}{4^2}+...+\frac{1}{4^{999}}\right)-\left(\frac{1}{4}+\frac{1}{4^2}+...+\frac{1}{4^{999}}+\frac{1}{4^{1000}}\right)\)
\(\Rightarrow3C=1-\frac{1}{4^{1000}}\)
\(\Rightarrow C=\left(1-\frac{1}{4^{1000}}\right).\frac{1}{3}\)
\(\Rightarrow C=\frac{1}{3}-\frac{1}{4^{1000}.3}\)
Mà \(\frac{1}{3}>\frac{1}{3}-\frac{1}{4^{1000}.3}\)
\(\Rightarrow C< \frac{1}{3}\)
Vậy \(C< \frac{1}{3}\)
Dùng cách SO SÁNH PHẦN HƠN nha bạn :)
Ta có: \(\frac{999}{556}-1=\frac{143}{556}\)
\(\frac{1000}{557}-1=\frac{143}{557}\)
Vì \(\frac{143}{556}>\frac{143}{557}\)nên \(\frac{999}{556}>\frac{1000}{557}\)<=> x>y
Ta có \(x=\frac{357}{-352}\)
\(\Rightarrow-x=\frac{357}{352}=1+\frac{2}{352}=\frac{1}{176}\)
Ta có \(y=\frac{-1000}{999}\)
\(\Rightarrow-y=\frac{1000}{999}=1+\frac{1}{999}\)
Vì \(\frac{1}{176}>\frac{1}{999}\Rightarrow1+\frac{1}{176}>1+\frac{1}{999}\Rightarrow-x>-y\Rightarrow x< y\)
Khi đó x < y
Vậy....
\(-x=\frac{357}{352}=1+\frac{5}{352}\)
\(-y=\frac{1000}{999}=1+\frac{1}{999}\)
\(\frac{5}{352}>\frac{5}{999}>\frac{1}{999}\)
\(=>\frac{357}{352}>\frac{1000}{999}=>-x>-y\)
\(=>x< y\)