Ôi bà con ơi, bài khó thế! Ai đồng ý với mik bài khó thì k mik nhé!

b) 15/16 = 1 - 1/16 = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 + 1/5 - 1/6 + 1/6 - 1/7 + ... + 1/14 - 1/15 + 1/15 - 1/16 
=1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + ... + 1/210 + 1/240 (mình cộng từng cặp số hạng lại, bạn tự quy đồng nhé) 
 

a) 25/27 = 1/3 +1/4 +1/6+1/12+1/18+1/27 
25/27 = (1/3+1/4+1/12) + (1/6+1/18)+1/27 = ( 8/12 )+( 4/18 )+1/27=18/27+ 6/27 +1/27=25/27 
=> 2/3=8/12=18/27 ; 4/18=2/9=6/27

Ta có:\(\frac{15}{16}=\frac{1}{16}+\frac{2}{16}+\frac{4}{16}+\frac{8}{16}=\frac{1}{16}+\frac{1}{8}+\frac{1}{4}+\frac{1}{2}\)

Bấm đúng nếu thấy đúng!thanks

a)11/15=5+3+3/15=5/15+3/15+3/15=1/3+1/5+1/5

b)15/16=4+8+2+2/16=4/16+8/16+2/16+2/16=1/4+1/2+1/8+1/8

\(a,\frac{31}{32}=\frac{1}{2}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{4}\)

\(b,\frac{25}{27}=\frac{1}{2}+\frac{1}{3}+\frac{1}{18}+\frac{1}{27}\)

a) \(\frac{31}{32}=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)

b) \(\frac{25}{27}=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{24}+\frac{1}{48}+\frac{1}{96}+\frac{1}{192}+\frac{1}{384}+\frac{1}{1152}+\frac{1}{3756}+...\)