Question

Tính

B= \(\frac{1}{25.27}\)+ \(\frac{1}{27.29}\)+ \(\frac{1}{29.31}\)+ ..... + \(\frac{1}{73.75}\)

Answer 1

B = \(\frac{1}{25}\)- \(\frac{1}{27}\)+ \(\frac{1}{27}\)-\(\frac{1}{29}\)+\(\frac{1}{29}\)-\(\frac{1}{31}\)+... + \(\frac{1}{73}\)-\(\frac{1}{75}\)=

B = \(\frac{1}{25}\)-\(\frac{1}{75}\)

B = \(\frac{2}{75}\)

Ủng hộ  mik nha, mk đg âm điểm nè

Answer 2

B = 1/2.(1/25-1/27+1/27-1/29+....+1/73-1/75)

    = 1/2.(1/25-1/75)

   =1/2.2/75

   = 1/75

kik cho mk nhé. đúng đấy. kb luôn

Answer 3

4/75 nha bn

Answer 4

Ta có : 

B=\(\frac{1}{25\cdot27}+\frac{1}{27\cdot29}+\frac{1}{29\cdot31}+.......+\frac{1}{73\cdot75}\)

\(\Rightarrow\)2B=\(\frac{2}{25\cdot27}+\frac{2}{27\cdot29}+\frac{2}{29\cdot31}+.....+\frac{2}{73\cdot75}\)

\(\Rightarrow\)2B=\(\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+\frac{1}{29}-\frac{1}{31}+....+\frac{1}{73}-\frac{1}{75}\)

\(\Rightarrow\)2B=\(\frac{1}{25}-\frac{1}{75}\)

\(\Rightarrow\)2B=\(\frac{2}{75}\)

\(\Rightarrow\)B=\(\frac{1}{75}\)

Answer 5

B=\(\frac{1}{25.27}+\frac{1}{27.29}+\frac{1}{29.31}+....+\frac{1}{73.75}\)

2B=\(\frac{2}{25.27}+\frac{2}{27.29}+\frac{2}{29.31}+....+\frac{2}{73.75}\)

2B=\(\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+\frac{1}{29}-....-\frac{1}{73}+\frac{1}{73}-\frac{1}{75}\)

2B=\(\frac{1}{25}-\frac{1}{75}\)

2B=\(\frac{2}{75}\)

B=\(\frac{1}{75}\)

Answer 6

mình làm văn tắt luôn nhé.

1/2(1/25-1/75)

1/2 . 2/75

=1/75

Answer 7

= 1/75

Answer 8

\(B=\frac{1}{25.27}+\frac{1}{27.29}+...+\frac{1}{73.75}\)

\(2B=\frac{2}{25.27}+\frac{2}{27.29}+...+\frac{2}{73.75}\)

\(2B=\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+.......+\frac{1}{73}-\frac{1}{75}\)

\(2B=\frac{1}{25}-\frac{1}{75}\)

\(2B=\frac{2}{75}\)

\(B=\frac{1}{75}\)