tim x biet (1/2+1/3+...+1/2014).x=2013/1+2012/2+...+1/2013
Toán lớp 7
cách làm 8 li-ke
tim x biet (1/2+1/3+...+1/2014).x=2013/1+2012/2+...+1/2013
Tim x biet x-1/2015 + x-2/2014= x-3/2013 + x-4/2012
=>(x-1)/2015 - 1 + (x-2(/2014 -1 = (x-3)/2013 -1 + (x-4)/2012 -1
=>(x-2016)*(1/2015+1/2014-1/2013-1/2012)=0
=>x=2016
Trừ 1 ở mỗi p/s,ta có:
\(\left(\frac{x-1}{2015}-1\right)+\left(\frac{x-2}{2014}-1\right)=\left(\frac{x-3}{2013}-1\right)+\left(\frac{x-4}{2012}-1\right)\)
\(\Leftrightarrow\left(\frac{x-2016}{2015}\right)+\left(\frac{x-2016}{2014}\right)=\left(\frac{x-2016}{2013}\right)+\left(\frac{x-2016}{2012}\right)\)
\(\Leftrightarrow\frac{x-2016}{2015}+\frac{x-2016}{2014}-\frac{x-2016}{2013}-\frac{x-2016}{2012}=0\)
\(\Leftrightarrow\left(x-2016\right)\left(\frac{1}{2015}+\frac{1}{2014}-\frac{1}{2013}-\frac{1}{2012}\right)=0\)
Vì \(\frac{1}{2015}+\frac{1}{2014}-\frac{1}{2013}-\frac{1}{2012}\ne0\)
=>x-2016=0
=>x=2016
Vậy..................
mình hỏi bài này :tìm số tự nhiên x biết :(x-2)^2014=(x-2)^2016
(1/2+1/3+1/4+....1/2014).x=2013/1+2012/2+...+2/2012+1/2013 tim x
ai lam dc minh cho 3 kich
thank cac ban
LÀM GẤP GIÚP MK HA, MK TICK CHO
x+3/2012 + x+2/2013 = x+1/2014 + x/2015 Tim x
Tìm x biết (2012/1+2011/2+...+1/2012)/(1/2+1/3+...+1/2013):x=-2013/2014
Tìm x bk :
( 1/2 + 1/3 + ... + 1/2014) x = 2013/1 + 2012/1 + ... + 2/2012 + 1/2013
Tìm x biết a |3-2x|=x+1
b (1/2+1/3+...+1/2014)×x=2013/1+2012/2+...+2/2012+1/2013
Tìm x biết: (1/2+1/3+1/4+...+1/2014).x =2013/1+2012/2+2011/3+...+2/2012+1/2013
trước tiên bạn phải tính:
2013/1+2012/2+2011/3+.....+2/2012+1/2013
=1+2012/2)+(1+2011/3)+.....+(1+2/2012)+(1+1/2013) +1 {BƯỚC NÀY TÁCH 2013 RA LÀM 2013SỐ1 ĐỂ CÔNG VS CÁC THỪA SỐ CÒN LẠI}
=2014/2+2014/3+...+2014/2012+2014/2013+2014/2014
=2014.(1/2+1/3+....+1/2012+1/20131/2014
suy ra x=2014