2008 . 2007 2007 - 2007 . 2006 2006 bài này làm sao vậy trời, chắc tui chết
giúp mik làm bài này với
cho A=\(\dfrac{2006}{2007}\)+\(\dfrac{2007}{2008}\)+\(\dfrac{2008}{2006}\)
A=20062007+20072008+20082009=1−12007+1−12008+1−12009�=20062007+20072008+20082009=1−12007+1−12008+1−12009
=3−12007−12008−12009
So sánh
2006 / 2007 + 2007/2008 và 2006 + 2007/2007+2008
2.006/2.007 + 2.007/2.008 < 2006 + 2.007/2.007 + 2.008
Chúc bạn học tốt.
😁😁😁
So sánh
bài 1 :A= 2006/2007-2007/2008+2008/2009-2009/2010
B= -1/2006*2007-1/2008*2009
bài 2: C= 2006/2007+2007/2008+2008/2009+2009/2006 với 4
So sanh A va B biet : A=2006/2007+2007/2008+2008/2009 va B=(2006+2007+2008)/(2007+2008+2009)
A>b
Cách làm: Bạn tách |B ra rồi so sánh với từng ps ở A, sau đó Kết luận
So sánh 2 biểu thức:
A = 2006/2007 + 2007/2008 + 2008/2009
B = 2006 + 2007 + 2008/2007 + 2008 + 2009
\(A=\frac{2006}{2007}+\frac{2007}{2008}+\frac{2008}{2009}=1-\frac{1}{2007}+1-\frac{1}{2008}+1-\frac{1}{2009}\)
\(=3-\frac{1}{2007}-\frac{1}{2008}-\frac{1}{2009}>1\).
\(B=\frac{2006+2007+2008}{2007+2008+2009}< \frac{2007+2008+2009}{2007+2008+2009}=1\).
Suy ra \(A>B\).
So sánh: x = 2006/2007 - 2007/2008 + 2008/2009 - 2009/2010.
y = - 1/(2006 × 2007) - 1/(2007 × 2008).
Ta có:
\(x=\dfrac{2006}{2007}-\dfrac{2007}{2008}+\dfrac{2008}{2009}-\dfrac{2009}{2010}\)
\(=\dfrac{2006.2008-2007^2}{2007.2008}+\dfrac{2008.2010-2009^2}{2009.2010}\)
\(=\dfrac{2006.2007+2006-2007^2}{2007.2008}+\dfrac{2008.2009+2008-2009^2}{2009.2010}\)
\(=\dfrac{2007\left(2006-2007\right)+2006}{2007.2008}+\dfrac{2009\left(2008-2009\right)+2008}{2009.2010}\)
\(=\dfrac{-1}{2007.2008}+\dfrac{-1}{2008.2010}< \dfrac{-1}{2006.2007}+\dfrac{1}{2007.2008}\)
\(\Rightarrow x< y\)
Vậy x < y
SO SÁNH : 2006/2007+2007/2008+2008/2009+2009/2006 VỚI 4
AI LÀM ĐƯỢC MÌNH TICK CHO
\(\frac{2006}{2007}+\frac{2007}{2008}+\frac{2008}{2009}+\frac{2009}{2006}\)
\(=\left(1-\frac{1}{2007}\right)+\left(1-\frac{1}{2008}\right)+\left(1-\frac{1}{2009}\right)+\left(1+\frac{3}{2006}\right)\)
\(=\left(1+1+1+1\right)-\left(\frac{1}{2007}+\frac{1}{2008}+\frac{1}{2009}\right)+\frac{3}{2006}\)
\(< 4-\left(\frac{1}{2006}+\frac{1}{2006}+\frac{1}{2006}\right)+\frac{3}{2006}\)
\(=4-\frac{3}{2006}+\frac{3}{2006}\)
\(=4\)
\(\Rightarrow\frac{2006}{2007}+\frac{2007}{2008}+\frac{2008}{2009}+\frac{2009}{2006}< 4\)
Gọi biểu thức trên là A
\(\frac{2006}{2007}=1-\frac{1}{2007}\)
\(\frac{2007}{2008}=1-\frac{1}{2008}\)
\(\frac{2008}{2009}=1-\frac{1}{2009}\)
\(\frac{2009}{2006}=1+\frac{3}{2006}\)
\(\Rightarrow A=4-\left(\frac{1}{2007}+\frac{1}{2008}+\frac{1}{2009}-\frac{3}{2006}\right)\)
\(\Rightarrow A< 4\)
Study well
Câu 1: So sánh các số hữu tỉ:
A = 2006/2007 - 2007/2008 + 2008/2009 - 2009/2010 với B = -1/2006 x 2007 - (-1)/2007 x 2008
Cho A= 2006/2007+2007/2008+2008/2006