2007x2006-8/2005x2007+1999
Bài 4: Tính nhanh:
\(\dfrac{2007x2006-8}{2005x2007+1999}\)
\(\dfrac{2006\times2007-8}{2005\times2007+1999}\)
= \(\dfrac{\left(2005+1\right)\times2007-8}{2005\times2007+1999}\)
= \(\dfrac{2005\times2007+2007-8}{2005\times2007+1999}\)
= \(\dfrac{2005\times2007+1999}{2005\times2007+1999}\)
= 1
2006x2006-2005x2007/2007x2006-2005x2006
?????????????????????????????????????????
Tính nhanh 2007x2006-1/2005×2007+2006
\(\dfrac{2007\times2006-1}{2005\times2007+2006}\)
\(=\dfrac{2007\times2006-1}{\left(2006-1\right)\times2007+2006}\)
\(=\dfrac{2007\times2006-1}{2006\times2007-2007+2006}\)
\(=\dfrac{2007\times2006-1}{2006\times2007-\left(2007-2006\right)}\)
\(=\dfrac{2007\times2006-1}{2007\times2006-1}\)
\(=1\)
\(\dfrac{2007x2006-1}{2005x2007+2006}\)
\(=\dfrac{2007x\left(2005+1\right)-1}{2005x2007+2006}\)
\(=\dfrac{2007x2005+2007-1}{2005x2007+2006}\)
\(=\dfrac{2007x2005+2006}{2005x2007+2006}=1\)
2005x2007-1 / 2004+2005x2006= ?
\(\frac{2005\times2007-1}{2004+2005\times2006}\)
\(=\frac{2005\times\left(2006+1\right)-1}{2004+2005\times2006}\)
\(=\frac{2005\times2006+2005\times1-1}{2004+2005\times2006}\)
\(=\frac{2005\times2006+2005-1}{2004+2005\times2006}\)
\(=\frac{2005\times2006+2004}{2004+2005\times2006}\)
\(=1\)
_Chúc bạn học tốt_
2005x2007-1/2004+2005x2006
tính nhanh 2005x2007-1/2004+2005x2006
1 / 2001x2003 + 1/2003x2005 + 1/2005x2007 +...+ 1/2011x2013
\(\dfrac{1}{2001.2003}+\dfrac{1}{2003.2005}+...+\dfrac{1}{2011.2013}\)
\(=\dfrac{1}{2}\left(\dfrac{2}{2001.2003}+\dfrac{1}{2003.2005}+...+\dfrac{1}{2011.2013}\right)\)
\(=\dfrac{1}{2}\left(\dfrac{1}{2001}-\dfrac{1}{2003}+\dfrac{1}{2003}-\dfrac{1}{2005}+...+\dfrac{1}{2011}-\dfrac{1}{2013}\right)\)
\(=\dfrac{1}{2}\left(\dfrac{1}{2001}-\dfrac{1}{2013}\right)=\dfrac{2}{1342671}\)
=1/2.(2/2001.2003+2/2003.2005+.....+2/2011.2013)
=1/2(1/2001-1/2003+1/2003-1/2005+....+1/2011-1/2013)
=1/2(1/2001-1/2013)
=2/1342671
Tính nhanh C = (2005x2007-1)/(2004+2005x2006)
C=(2005x2006+2005-1)/(2004+2005x2006)=
(2005x2006+2004)/(2004+2005x2006)=1
rồi cảm ơn tôi đã làm trước khi cậu ra đáp án
tính giá trị của biểu thức: A=2005x2007-1/2004+2005x2006
A = \(\frac{2005\times2007-1}{2004+2005\times2006}=\frac{2005\times\left(2006+1\right)-1}{2004+2005\times2006}=\frac{2005\times2006+2005-1}{2004+2005\times2006}\)
\(=\frac{2005\times2006+2004}{2004+2005\times2006}=1\)
không tính kết quả hay so sánh
M:2005x2007
N:2006x2006
M=(2006-1)x(2006+1)=2006x2006-2006+2006-1=2006x2006-1
M=2006x2006-1
N=2006x2006
Vậy M<N