so sánh A= \(\frac{20^{10}+1}{20^{10}-1}\)va B= \(\frac{20^{10}-1}{20^{10}-3}\)
So sánh : \(A =\frac{20^{10} +1}{20^{10}-1} ; B =\frac{20^{10} -1}{20^{10} -3}\)
\(A=\frac{20^{10}+1}{20^{10}-1}=\frac{20^{10}-1}{20^{10}-1}+\frac{2}{20^{10}-1}=1+\frac{2}{20^{10}-1}\)
\(B=\frac{20^{10}-1}{20^{10}-3}=\frac{20^{10}-3}{20^{10}-3}+\frac{2}{20^{10}-3}=1+\frac{2}{20^{10}-3}\)
\(20^{10}-1>20^{10}-3\Rightarrow\frac{2}{20^{10}-1}< \frac{2}{20^{10}-3}\)
=> A < B
so sánh \(A=\frac{20^{10}+1}{20^{10}-1};B=\frac{20^{10}-1}{20^{10}-3}\)
Lời giải:
$A=\frac{20^{10}-1+2}{20^{10}-1}=1+\frac{2}{20^{10}-1}< 1+\frac{2}{20^{10}-3}=\frac{20^{10}-1}{20^{10}-3}=B$
Vậy $A< B$
So sánh A và B:
\(A=\frac{20^{10}+1}{20^{10}-1};B=\frac{20^{10}-1}{20^{10}-3}\)
So sánh A=\(\frac{20^{10}+1}{20^{10}-1}\)và B=\(\frac{20^{10}-1}{20^{10}-3}\)
ta thấy B>1 nên B=\(\frac{20^{10}-1}{20^{10}-3}\)>\(\frac{20^{10}-1+2}{20^{100}-3+2}\)=\(\frac{20^{10}+1}{20^{10}-1}\)=A
vậy B>A
nếu ko hiểu thì tham khảo trong SBT lớp 6 bài so sánh PS ấy
So sánh : A=\(\frac{20^{10}+1}{20^{10}-1}\)và B=\(\frac{20^{10}-1}{20^{10}-3}\)
Vì \(20^{10}-1>20^{10}-3\)
\(\Rightarrow B=\frac{20^{10}-1}{20^{10}-3}>\frac{20^{10}-1+2}{20^{10}-3+2}=\frac{20^{10}+1}{20^{10}-1}=A\)
vậy \(A< B\)
So sánh: \(A=\frac{20^{10}+1}{20^{10}-1};B=\frac{20^{10}-1}{20^{10}-3}\)
Ta co B>1
=>A=20^10+1'20^10-1<20^10+1/2010-3+1
=>A<20^10+1/20^10-3+1
=>A<20^10-1/20^10-3
=>A<B
Vậy A<B
So sánh :
\(A=\frac{20^{10}+1}{20^{10}-1}vàB=\frac{20^{10-1}}{20^{10}-3}\)
Ta có:
\(A=\frac{20^{10}+1}{20^{10}-1}=\frac{20^{10}-1+2}{20^{10}-1}=1+\frac{2}{20^{10}-1}\)
\(B=\frac{20^{10}-1}{20^{10}-3}=\frac{20^{10}-3+2}{20^{10}-3}=1+\frac{2}{20^{10}-3}\)
Ta lại có:
\(20^{10}-1>20^{10}-3\Rightarrow\frac{2}{2^{10}-1}< \frac{2}{2^{10}-3}\Rightarrow1+\frac{2}{2^{10}-1}< 1+\frac{2}{2^{10}-3}\)
Hay A<B
So Sánh \(A=\frac{20^{10}+1}{20^{10}-1}\text{và }B=\frac{20^{10}-1}{20^{10}-3}\)
A = \(\frac{2^{10}+1}{2^{10}-1}=\frac{2^{10}-1+2}{2^{10}-1}=1+\frac{2}{2^{10}-1}\)
B = \(\frac{2^{10}-1}{2^{10}-3}=\frac{2^{10}-3+2}{2^{10}-3}=1+\frac{2}{2^{10}-3}\)
Vì \(\frac{2}{2^{10}-1}
So sánh A và B
A = \(\frac{20^{10}+1}{20^{10}-1}\)Và B = \(\frac{20^{10}-1}{20^{10}-3}\)
Ta có:
\(A=\frac{20^{10}+1}{20^{10}-1}=1\)
\(B=\frac{20^{10}-1}{20^{10}-3}=1\)
Vậy A và B bằng nhau
Tính A và B rồi ta so sánh:
A = \(\frac{20^{10}+1}{20^{10}-1}\) = \(1\)
B = \(\frac{20^{10}-1}{20^{10}-3}\) = \(1\)
Mà \(1\) = \(1\)
Nên: A = B
A=(20^10+1/20^10-1)=(20^10-1+2/20^10-1)=(20^10-1/20^10-1)+(2/20^10-1)=1+(2/20^10-1).
Tương tự ,B=1+(2/20^10-3).
Vì 2/20^10-1>2/20^10-3(vì 20^10-1>20^10-3).
=>A<B.
Vậy A<B.
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