giúp tính \(\dfrac{2}{2x4}+\dfrac{2}{4x6}x...x\dfrac{2}{2014x2016}\)
Tính : 2/2x4+2/4x6+2/6x8+....+2/2014x2016
2/2x4+ 2/4x6+ 2/6x8+...+2/2014x2016
=1/2-1/4+1/4-1/6+1/6-1/8+...+1/2014-1/2016
=1/2-1/2016
=1008/2016-1/2016
=1007/2016
Tính: 2/2x4+2/4x6+2/6x8+.............2/2014x2016
\(\frac{2}{2x4}+\frac{2}{4x6}+\frac{2}{6x8}+...+\frac{2}{2014x2016}\)
\(=\frac{4-2}{2x4}+\frac{6-4}{4x6}+\frac{8-6}{6x8}+...+\frac{2016-2014}{2014x2016}\)
\(=\frac{4}{2x4}-\frac{2}{2x4}+\frac{6}{4x6}-\frac{4}{4x6}+\frac{8}{6x8}-\frac{6}{6x8}+...+\frac{2018}{2016x2018}-\frac{2016}{2016x2018}\)
\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{2016}-\frac{1}{2018}\)
\(=\frac{1}{2}-\frac{1}{2018}\)
\(=\frac{504}{1009}\)
Tính: 2/2x4+2/4x6+2/6x8+...+2/2014x2016
Giúp mk nhanh lên! Mk tik cho!`Please`
= 2 ( 1/2 x 4 + 1/4 x 6 + .... + 1/2014 x 2016 )
= 4 ( 1/2 - 1/4 + 1/4 - 1/6 + .... + 1/2014 - 1/2016 )
= 4 ( 1/2 - 1/2016 )
= 4 x 1507/2016
= 1507/504
= 2( 1/2*4 + 1 /4*6 +...+1/2014*2016)
=4(1/2-1/4+1/4-1/6+...+1/2014-1/2016)
=4(1/2-1/2016)
=4*1507/2016
= tu tinh nghen
2/2x4+2/4x6+2/6x8..................2/2014x2016
TA có
4-2/2*4+6-4/4*6+8-6/6*8+...+2016-2014/2014*2016
=1/2-1/4+1/4-1/6+...+1/2014-1/2016
=1/2+1/4-1/4+1/6-1/6+...+1/2014-1/2014-1/2016
=1/2-1/2016
=1007/2016
2/2x4+2/4x6+2/6x8+......................+2/2014x2016
=1/2-`1/4+1/4-1/6+1/6-1/8 +..............................+1/2014-1/2016
=1/2-1/2016
=1007/2016
2/2x4+2/4x6+2/6x8+....+2/2014x2016
đặt biểu thức đó là A
ta có A=\(\frac{2}{2x4}+\frac{2}{4x6}+...+\frac{2}{2014x2016}\)
\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{12}+...+\frac{1}{2014}-\frac{1}{2016}\)
=\(\frac{1}{2}-\frac{1}{2016}\)
=1007/2016
k nha đúng đấy
2/2x4+2/4x6+2/6x8+ . . . + 2/2014x2016
2/2x4+2/4x6+2/6x8+...+2/2014x2016
= 1/2-1/4+1/4-1/6+...+1/2014-1/2016
= 1/2- 1/2016
= 1007/2016
mk trả lời đầu tiên đó . k nhé ai k mk mk k lại
Bằng 1007/2016 nha bạn k mk nha kết bạn vs lun mk hết lượt rùi
2/2x4 + 2/4x6 + 2/6x8 +...+2/2014x2016
2/2x4+2/4x6+2/6x8+...+2/2014x2016
=1/2-1/4+1/4-1/6+1/6-1/8+...+1/2014-1/2016
=1/2-1/2016
=1007/2016
Tích mk nha bn
2/2x4+2/4x6+2/6x8+...+2/2014x2016=?
So sánh
B=\(\dfrac{1}{2x4}\)+\(\dfrac{1}{4x6}\)+.....+\(\dfrac{1}{46x48}\) với \(\dfrac{1}{4}\)
\(B=\dfrac{1}{2\cdot4}+\dfrac{1}{4\cdot6}+...+\dfrac{1}{46\cdot48}\)
\(=\dfrac{1}{2}\left(\dfrac{2}{2\cdot4}+\dfrac{2}{4\cdot6}+...+\dfrac{2}{46\cdot48}\right)\)
\(=\dfrac{1}{2}\left(\dfrac{1}{2}-\dfrac{1}{48}\right)\)
\(=\dfrac{1}{2}\cdot\dfrac{23}{48}=\dfrac{23}{96}< \dfrac{1}{4}\)