40

60             Hok tốt !!!!

30

3

2

ai tích mình mình tích lại cho

4x6+16=40

5x7+25=60

20:4x6=30

30:5:2=3

40:4:5=2

1007/2016

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

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

= 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

\(\frac{1007}{2016}\)

Bằng 1007/2016 nha bạn k mk nha kết bạn vs lun mk hết lượt rùi

2/2×4 + 2/4×6 + ... + 2/16×18 + 2/18×20

= 1/2 - 1/4 + 1/4 - 1/6 + ... + 1/16 - 1/18 + 1/18 - 1/20

= 1/2 - 1/20

= 10/20 - 9/20

= 9/20

2/2x4+2/4x6+...+2/16x18+2/18x20

=1/2=1/4+1/4-1/6+...+1/16-1/18+1/18-1/20

=1/2-1/20

=10/20-9/20

=1/20

2/2x4 + 2/4x6 + .....+ 2/16x18 + 2/18x20

=1/2-1/4+1/4-1/6+...+1/18-1/20

=1/2-1/20

=9/20

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

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

\(\frac{2}{2x4}+\frac{2}{4x6}+\frac{2}{6x8}+...+\frac{2}{2014x2016}\)

\(=\frac{4-2}{2x4}+\frac{6-4}{4x6}+\frac{8-6}{6x8}+...+\frac{2016-2014}{2014x2016}\)

\(=\frac{4}{2x4}-\frac{2}{2x4}+\frac{6}{4x6}-\frac{4}{4x6}+\frac{8}{6x8}-\frac{6}{6x8}+...+\frac{2018}{2016x2018}-\frac{2016}{2016x2018}\)

\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+\frac{1}{6}-\frac{1}{8}+...+\frac{1}{2016}-\frac{1}{2018}\)

\(=\frac{1}{2}-\frac{1}{2018}\)

\(=\frac{504}{1009}\)

\(\frac{2}{5}\times\frac{3}{4}\times\frac{6}{15}:\frac{4}{9}\times5=\frac{2\times3\times6\times9\times5}{5\times4\times15\times4}=\frac{27}{20}\)

2/5 x 3/4 x 6/15 : 4/9 x 5 = 6/20 x 6/15 : 4/9 x 5 = 36/300 : 4/9 x 5 = 324/1200 x 5 = 1620/1200