Bài 2:

\(\frac{13}{36}=\frac{1+5+7}{36}=\frac{1}{36}+\frac{5}{36}+\frac{7}{36}\)

\(\frac{31}{60}=\frac{1+23+7}{60}=\frac{1}{60}+\frac{23}{60}+\frac{7}{60}\)

Bài 1:

\(\frac{25}{27}=\frac{1+3+9+3+9}{27}=\frac{1}{27}+\frac19+\frac13+\frac19+\frac13\)

\(\frac{15}{16}=\frac{8+7}{16}=\frac12+\frac{7}{16}=\frac12+\frac{4+3}{16}=\frac12+\frac14+\frac{3}{16}\)

\(=\frac12+\frac14+\frac{2+1}{16}=\frac12+\frac14+\frac18+\frac{1}{16}\)

a: \(\frac{13}{27}=\frac{1}{27}+\frac{12}{27}=\frac{1}{27}+\frac49=\frac{1}{27}+\frac{3+1}{9}=\frac{1}{27}+\frac39+\frac19\)

\(=\frac{1}{27}+\frac19+\frac13\)

b: \(\frac{15}{16}=\frac{1}{16}+\frac{14}{16}\)

\(=\frac{1}{16}+\frac78=\frac{1}{16}+\frac{4+3}{8}=\frac{1}{16}+\frac48+\frac38\)

\(=\frac{1}{16}+\frac12+\frac{2+1}{8}=\frac{1}{16}+\frac12+\frac14+\frac18\)

c: \(\frac{39}{54}=\frac{38+1}{54}=\frac{38}{54}+\frac{1}{54}\)

\(=\frac{1}{54}+\frac{19}{27}=\frac{1}{54}+\frac{1}{27}+\frac{18}{27}\)

\(=\frac{1}{54}+\frac{1}{27}+\frac23=\frac{1}{54}+\frac{1}{27}+\frac46=\frac{1}{54}+\frac{1}{27}+\frac36+\frac16\)

\(=\frac{1}{54}+\frac{1}{27}+\frac16+\frac12\)

d: \(\frac{13}{42}=\frac{6+7}{42}=\frac{6}{42}+\frac{7}{42}=\frac17+\frac16\)

a) \(\frac{13}{35}=\frac{\left(5+7+1\right)}{35}=\frac{5}{35}+\frac{7}{35}+\frac{1}{35}=\frac{1}{7}+\frac{1}{5}+\frac{1}{35}\)

b) \(\frac{15}{16}=\frac{\left(2+4+8+2\right)}{16}=\frac{2}{16}+\frac{4}{16}+\frac{8}{16}+\frac{2}{16}=\frac{1}{8}+\frac{1}{4}+\frac{1}{2}+\frac{1}{8}\)

tick cho ai bây giờ hề hề mình kết bạn với ai thì mình tick cho người đó

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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 :

\(1=\frac{1}{2}+\frac{1}{2}=\frac{1}{4}+\frac{1}{4}+\frac{1}{4}+\frac{1}{4}\)

\(\frac{1}{3}:\frac{1}{4}=\frac{1}{12}\)

\(\frac{1}{12}\cdot4=\frac{1}{3}\)

\(\frac{1}{12}\cdot3+\frac{1}{12}=\frac{1}{3}\Rightarrow\frac{1}{12}+\frac{1}{4}=\frac{1}{3}\)

Hai phân số đó là 1/12 và 1/4

1 . Tổng của hai phân số là

1/3=1/2+1/6

a)1/2+1/3

b)1/3+1/4

c)1/3+1/5

k nhé bn.chúc bn học giỏi