so sánh :
1) A=102013-1/102014-1
B= 102012+1/102013+1
2) C=20011/2012 + 2012/2013
D=2011+2012/2012+2013
so sánh phân số
A=2012^2012+1 trên 2012^2013+1
B=2012^2011+1 trên 2012^2013+1
So sánh A và B biết :
A= 20112012-200112011
B=20112013- 20112012
Ta có:
\(A=2011^{2012}-2011^{2011}=2011^{2011}.\left(2011-1\right)\)
\(B=2011^{2013}-2011^{2012}=2011^{2012}.\left(2012-1\right)\)
Vì \(2011^{2011}< 2011^{2012}\Rightarrow A< B\)
Nhầm nha : \(B=2011^{2012}.\left(2011-1\right)\)
So sánh :
A = 2011^2011 + 1 / 2011^2012 + 1 và B = 2011^2012 + 1 / 2011^2013 + 1
so sánh :A= 2010/2011+2011/2012+2012/2013; B= 1/2+1/4+...+1/17
So sánh 2 phân số :
\(A=\frac{2012^{2012}+1}{2012^{2013}+1}\) và \(B=\frac{2012^{2011}+1}{2012^{2012}+1}\)
ÁP DỤNG CÔNG THỨC NẾU \(\frac{a}{b}\)>1 thì
\(\frac{a}{b}\)>\(\frac{a+m}{b+m}\)
Ta có : \(\frac{2012^{12}+1}{2012^{13}+1}\)>\(\frac{2012^{12}+1+2011}{2012^{13}+1+2011}\)=\(\frac{2012^{12}+2012}{2012^{13}+2012}\)=\(\frac{2012.\left(2012^{11}+1\right)}{2012.\left(2012^{12}+1\right)}\)
rồi rút gọn thành \(\frac{2012^{11}+1}{2012^{12}+1}=B\)
Vậy A>B
Nhớ cho mình đúng nha
Ta có:\(A=\dfrac{2012^{2012}+1}{2012^{2013}+1}\)
\(\Rightarrow2012.A=\dfrac{2012^{2013}+2012}{2012^{2013}+1}=\dfrac{2012^{2013}+1+2011}{2012^{2013}+1}=1+\dfrac{2011}{2012^{2013}+1}\)Ta có:\(B=\dfrac{2012^{2011}+1}{2012^{2012}+1}\)
\(\Rightarrow2012.B=\dfrac{2012^{2012}+2012}{2012^{2012}+1}=\dfrac{2012^{2012}+1+2011}{2012^{2012}+1}=1+\dfrac{2011}{2012^{2012}+1}\)Vì\(\dfrac{2011}{2012^{2013}+1}< \dfrac{2011}{2012^{2012}+1}\)
\(\Rightarrow1+\dfrac{2011}{2012^{2013}+1}< 1+\dfrac{2011}{2012^{2012}+1}\)
\(\Rightarrow\dfrac{2012^{2012}+1}{2012^{2013}+1}< \dfrac{2012^{2011}+1}{2012^{2012}+1}\)
Vậy A<B
So sánh 2 số sau: M=\(\frac{2013^{2012}+2012}{2013^{2011}+1}\)và \(N=\frac{2013^{2011}+2012}{2013^{2010}+1}\)
Ta có :
\(\frac{1}{2013}M=\frac{2013^{2012}+2012}{2013^{2012}+2013}=\frac{2013^{2012}+2013}{2013^{2012}+2013}-\frac{1}{2013^{2012}+2013}=1-\frac{1}{2013^{2012}+2013}\)
Lại có :
\(\frac{1}{2013}N=\frac{2013^{2011}+2012}{2013^{2011}+2013}=\frac{2013^{2011}+2013}{2013^{2011}+2013}-\frac{1}{2013^{2011}+2013}=1-\frac{1}{2013^{2011}+2013}\)
Vì \(\frac{1}{2013^{2012}+2013}< \frac{1}{2013^{2011}+2013}\) nên \(M=1-\frac{1}{2013^{2012}}>N=1-\frac{1}{2013^{2011}+2013}\)
Vậy \(M>N\)
Chúc bạn học tốt ~
So sánh A và B biết : \(A=\frac{2012^{2012}+1}{2012^{2013}+1};B=\frac{2012^{2011}+1}{2012^{2012}+1}\)
\(10A=\frac{2012^{2013}+10}{2012^{2013}+1}=\frac{2012^{2013}+1+9}{2012^{2013}+1}=1+\frac{9}{2012^{2013}+1}\)
\(10B=\frac{2012^{2012}+10}{2012^{2012}+1}=\frac{2012^{2012}+1+9}{2012^{2012}+1}=1+\frac{9}{2012^{2012}+1}\)
Vì \(\frac{9}{2012^{2013}+1}
ta co A=\(\frac{2012^{2012}+1}{2012^{2013}+1}< \frac{2012^{2012}+1+2011}{2012^{2013}+1+2011}\)=\(\frac{2012^{2012}+2012}{2012^{2013}+2012}=\frac{2012\left(2012^{2011}+1\right)}{2012\left(2012^{2012}+1\right)}\)
=>A<B
so sánh A=2013^2010+1/2013^2011+1 và B=2013^2011-2/2013^2012-2
So sánh : A = 2011+2012/2012+2013 và B = 2011/2012+2012/2013
Ta có :
B = \(\dfrac{2011}{2012}\) + \(\dfrac{2012}{2013}\) .
\(\dfrac{2011}{2012}\) > \(\dfrac{2011}{2012+2013}\) .
\(\dfrac{2012}{2013}\) > \(\dfrac{2012}{2012+2013}\) .
\(\Rightarrow\) A < B .
Ta có :
B = 2012201320122013 .
20112012+201320112012+2013 .
20122012+201320122012+2013 .
⇒⇒ A < B .
Giải:
Ta có:
\(A=\dfrac{2011+2012}{2012+2013}\)
\(A=\dfrac{2011}{2012+2013}+\dfrac{2012}{2012+2013}\)
Vì \(\dfrac{2011}{2012}>\dfrac{2011}{2012+2013}\)
\(\dfrac{2012}{2013}>\dfrac{2012}{2012+2013}\)
\(\Rightarrow A< B\)