so sánh
\(x=\frac{-17}{23}\) và \(y=\frac{-171717}{232323}\)
\(x=\frac{-2009}{2010}\) và \(y=\frac{2010}{-2009}\)
So sánh:
a) \(\frac{-22}{45}\)và \(\frac{-51}{103}\)
b) \(\frac{2009^{2009}+1}{2009^{2010}+1}\)và \(\frac{2009^{2010}-2}{2009^{2011}-2}\)
c) \(\frac{2010}{2011}\)+ \(\frac{2011}{2012}\)+ \(\frac{2012}{2013}\)và \(\frac{2010+2011+2012}{2011+2012+2013}\)
d)\(\frac{121212}{171717}\)+ \(\frac{2}{7}\)- \(\frac{404}{1717}\)và \(\frac{10}{17}\)
\(b)\) Ta có công thức :
\(\frac{a}{b}< \frac{a+c}{b+c}\)\(\left(a,b,c\inℕ^∗\right)\)
Áp dụng vào ta có :
\(\frac{2009^{2010}-2}{2009^{2011}-2}< \frac{2009^{2010}-2+2011}{2009^{2011}-2+2011}=\frac{2009^{2010}+2009}{2009^{2011}+2009}=\frac{2009\left(2009^{2009}+1\right)}{2009\left(2009^{2010}+1\right)}=\frac{2009^{2009}+1}{2009^{2010}+1}\)
Vậy \(\frac{2009^{2009}+1}{2009^{2010}+1}>\frac{2009^{1010}-2}{2009^{2011}-2}\)
Chúc bạn học tốt ~
Àk mình còn thiếu một điều kiện nữa xin lỗi nhé :
Ta có công thức :
\(\frac{a}{b}< \frac{a+c}{b+c}\)\(\left(\frac{a}{b}< 1;a,b,c\inℕ^∗\right)\)
Bạn thêm vào nhé
So sánh 2 số hữu tỉ \(x=\frac{-2009}{2010}\) và \(y=\frac{2010}{-2009}\) ta được x.............y
vi \(\frac{-2009}{2010}>\frac{-2010}{1010}=1\)
\(\frac{2010}{-2009}=\frac{-2010}{2009}
cho 2 số hữu tỉ :
x= \(\frac{-17}{23}\) và y = \(\frac{-171717}{232323}\)
so sánh x và y
\(x=\frac{-17}{23}\)
\(y=\frac{-171717}{232323}=\frac{\left(-171717\right):10101}{232323:10101}=\frac{-17}{23}\)
\(\Rightarrow x=y\)
So sánh \(\frac{2008}{2009}+\frac{2009}{2010}và\frac{2008+2009}{2009+2010}\)
So sánh : A=\(\frac{2008}{2009}\)+\(\frac{2009}{2010}\)+\(\frac{2010}{2011}\)và B=\(\frac{2008+2009+2010}{2009+2010+2011}\)
\(B=\frac{2008+2009+2010}{2009+2010+2011}\)
\(=\frac{2008}{2009+2010+2011}+\frac{2009}{2009+2010+2011}+\frac{2010}{2009+2010+2011}\)
\(< \frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}=A\)
\(B=\frac{2008+2009+2010}{2009+2010+2011}\)
\(=\frac{2008}{2009+2010+2011}=\frac{2009}{2009+2010+2011}=\frac{2010}{2009+2010+2011}\)
\(< A=\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}\)
so sánh \(\frac{-22}{45}\)và\(\frac{-51}{103}\)
so sánh \(\frac{2009^{2009}+1}{2009^{2010}+1}\)và\(\frac{2009^{2010}-2}{2009^{2011}-2}\)
So sánh : \(A=\frac{2008}{2009}+\frac{2009}{2010}+\frac{2010}{2011}vàB=\frac{2008+2009+2010}{2009+2010+2011}\)
ko quy đồng hãy so sánh \(A=\frac{-5}{10^{2009}}+\frac{-17}{10^{2010}}vàB=\frac{-17}{10^{2009}}+\frac{-5}{10^{2010}}\)
cu lay phep tinh nay tru phep tinh kia hk ra thi nt hoi mink
So sánh:
A=\(\frac{2009^{2009}+1}{2009^{2010}+1}\)và B=\(\frac{2009^{2010}-2}{2009^{2011}-2}\)
\(B=\frac{2009^{2010}-2}{2009^{2011}-2}< 1\)
\(\Rightarrow B=\frac{2009^{2010}-2}{2009^{2011}-2}< \frac{2009^{2010}-2+2011}{2009^{2011}-2+2011}=\frac{2009^{2010}+2009}{2009^{2011}+2009}\)\(=\frac{2009.\left(2009^{2009}+1\right)}{2009.\left(2009^{2010}+1\right)}=\frac{2009^{2009}+1}{2009^{2010}+1}\)
Suy ra : \(\frac{2009^{2010}-2}{2009^{2011}-2}< \frac{2009^{2009}+1}{2009^{2010}+1}\) hay \(B< A\)
Vậy \(A>B\)