N
12
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Các câu hỏi dưới đây có thể giống với câu hỏi trên
TT
0
PN
2
13 tháng 7 2015
Công thức a/b >1 => a/b > a+n/b+n (a, b,n \(\in\) N*)
B = 2010-1/2010-3 > 1 nên B = 2010-1/2010-3 > 2010-1+2/2010-3+2 = 2010+1/ 2010-1 = A
Vậy A < B
HQ
5
18 tháng 5 2016
C2:A=\(\frac{20^{10}+1}{20^{10}-1}\) B=\(\frac{20^{10}-1}{20^{10}-3}\)
A=\(\frac{20^{10}-1+2}{20^{10}-1}\) B=\(\frac{20^{10}-3+2}{20^{10}-3}\)
A=\(\frac{20^{10}-1}{20^{10}-1}\)+\(\frac{2}{20^{10}-1}\) B=\(\frac{20^{10}-3}{20^{10}-3}\)+\(\frac{2}{20^{10}-3}\)
A=1+\(\frac{2}{20^{10}-1}\) B=1+\(\frac{2}{20^{10}-3}\)
Vì 2010-1>2010-3=>\(\frac{2}{20^{10}-1}\)<\(\frac{2}{20^{10}-3}\)
=>1+\(\frac{2}{20^{10}-1}\)<1+\(\frac{2}{20^{10}-3}\)
=>A<B(đây là cách để đi thi còn cách kia làm cho nhanh thôi)
18 tháng 5 2016
Vì B=\(\frac{20^{10}-1}{20^{10}-3}\)>1
Theo công thức \(\frac{a}{b}\)>1=>\(\frac{a+n}{b+n}\)>\(\frac{a}{b}\)
=>B>\(\frac{20^{10}-1+2}{20^{10}-3+2}\)
=>B>\(\frac{20^{10}+1}{20^{10}-1}\)=A
Vậy B>A
TT
1
3 tháng 5 2016
\(A=\frac{20^{10}+1}{20^{10}-1}>1\) và \(B=\frac{20^{10}-1}{20^{10}-3}>1\Rightarrow A=\frac{20^{10}+1}{20^{10}-1}>\frac{20^{10}+1-2}{20^{10}-1-2}=\frac{20^{10}-1}{20^{10}-3}=B\)
\(\Rightarrow A>B\)
V
1
5 tháng 8 2018
ta có: 2010 + 1 > 2010 - 1
\(\Rightarrow A=\frac{20^{10}+1}{20^{10}-1}>1\)
Lại có: 2010 -1 < 2010 - 3
\(\Rightarrow B=\frac{20^{10}-1}{20^{10}-3}< 1\)
=> A > B
HL
0
TL
6
MT
18 tháng 7 2015
\(A=\frac{2^{10}+1}{2^{10}-1}=\frac{2^{10}-1}{2^{10}-1}+\frac{2}{2^{10}-1}=1+\frac{2}{2^{10}-1}\)
\(B=\frac{2^{10}-1}{2^{10}-3}=\frac{2^{10}-3}{2^{10}-3}+\frac{2}{2^{10}-3}=1+\frac{2}{2^{10}-3}\)
\(\text{Vì }2^{10}-1>2^{10}-3\text{ nên }1+\frac{2}{2^{10}-1}<1+\frac{2}{2^{10}-3}\)
Vậy A<B
KS
3
15 tháng 6 2016
Đặt \(x=20^{10}\)
Xét hiệu a - b: \(H=\frac{a+1}{a-1}-\frac{a-1}{a-3}=\frac{\left(a+1\right)\left(a-3\right)-\left(a-1\right)^2}{\left(a-1\right)\left(a-3\right)}=\frac{-2}{\left(a-1\right)\left(a-3\right)}< 0\)
Vậy a<b
TM
0
Vì: A= 2010+1/ 2010 - 1 =1
B = 2010 -1/ 2010-3 = 1
Vì vaäy A= B
Mình nhầm, mình sẽ sủa lại:
Ta đã biết a/b >1 => a/b > a+n/b+n(a, b,n thuộc N*)
B = 2010-1/2010-3 > 1 nên B = 2010-1/2010-3 > 2010-1+2/2010-3+2
= 2010+1/ 2010-1 = A
Vậy B > A
A = 20^10 + 1 / 20^10 - 1 > 1
B = 20^10 - 1 / 20^10 - 3 > 1
Ta có: A = 20^10 + 1 / 20^10 - 1 > 20^10 + 1 - 2 / 20^10 - 1 - 2 = 20^10 - 1 / 20^10 - 3
Vậy A > B
Ta có: a/b > 1 => a/b > a+n/b+n { a,b,n thuộc N }
Vậy B= 20^10-1/20^10-3 > 20^10-1+2 / 20^10-3+2 = 20^10+1 / 20^10-1 = A
Kết luận B>A
Mình sẵn sàng trả lời mọi câu hỏi. Nhưng có những câu mình ko trả lời đc thì mong bạn thông cảm
mk có cách làm khác mấy bạn trên!!!!@@@
Các bạn toàn chép ở đằng sau sách đúng không!!
Ta có: A=\(\frac{20^{10}+1}{20^{10}-1}\)=\(1\frac{2}{20^{10}-1}\)(1)
B=\(\frac{20^{10}-1}{20^{10}-3}\)=\(1\frac{2}{20^{10}-3}\)(2)
Vì \(\frac{2}{20^{10}-1}\)<\(\frac{2}{20^{10}-3}\)(3)
Nên từ (1),(2),(3) suy ra A<B
Vậy A<B
MK làm đúng đó
Nguyễn Phương Thảo làm đúng rồi đó
rffffffffddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddwewwswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswwswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswswsws
Ta có
A-1=(20^10+1/20^10-1)-1
=20^10+1/20^10-1-20^10-1/20^10-1
=20^10+1-(20^10-1)/20^10-1
=20^10+1-20^10+1/20^10-1
=2/20^10-1
Lại có:
B-1=(20^10-1/20^10-3)-1
=20^10-1/20^10-3-20^10-3/20^10-3
=20^10-1-(20^10-3)/20^10-3
=20^10-1-20^10+3/20^10-3
=2/20^10-3
Nhận thấy
2/20^10-1<2/20610-3(vì 20^10-1>20^10-3)
=>A-1<B-1
=>A<B
Ta có: \(B=\frac{20^{10}-1}{20^{10}-3}>1\)
\(\Rightarrow\)Ta có: \(B=\frac{20^{10}-1}{20^{10}-3}>\frac{20^{10}-1-2}{20^{10}-3-2}=\frac{20^{10}+1}{20^{10}-1}=A\)
\(\Rightarrow A< B\)
I don't know ok