vì -3737/5151=\(\frac{-37.101}{51.101}\) =-37/51

-373737  /   515151=\(\frac{-37.10101}{51.10101}\) =-37/51

=>-3737/5151=-373737/515151

ok

a,\(-\frac{15}{21}=-\frac{5}{7};-\frac{55}{77}=-\frac{5}{7}\Rightarrow-\frac{15}{21}=-\frac{55}{77}\)

b, \(-\frac{3737}{5151}=-\frac{37}{51};-\frac{373737}{515151}=-\frac{37}{51}\Rightarrow-\frac{3737}{5151}=-\frac{373737}{515151}\)

a,-15/21=-5/7

   -55/77=-5/7

\(\frac{-15}{21}=\frac{-15\div3}{21\div3}=\frac{-5}{7}\)

\(\frac{-55}{77}=\frac{-55\div11}{77\div11}=\frac{-5}{7}\)

Vì \(\frac{-5}{7}=\frac{-5}{7}\Rightarrow\frac{-15}{21}=\frac{-55}{77}\)

b , \(\frac{-3737}{5151}=\frac{-3737\div101}{5151\div101}=\frac{-37}{51}\)

\(\frac{-373737}{515151}=\frac{-373737\div10101}{515151\div10101}=\frac{-37}{51}\)

Vì \(\frac{-37}{51}=\frac{-37}{51}\Rightarrow\frac{-3737}{5151}=\frac{-373737}{515151}\)

18.\(\left(\dfrac{3737}{4242}+\dfrac{3737}{5656}+\dfrac{3737}{7272}\right)\)

=18.\(\left(\dfrac{37}{42}+\dfrac{37}{56}+\dfrac{37}{72}\right)\)

=18.\(\dfrac{37}{18}\)

=37

`18 . (3737/4242+3737/5656+3737/7272)`

`=18. ( (37.101)/(42.101) + (37.101)/(56.101) + (37.101)/(72.101))`

`=18. (37/42+37/56 +37/72)`

`=18 . 37 . (1/42+1/56+1/72)`

`=18 . 37 . 1/18`

`=37`

\(18\cdot\left(\dfrac{3737}{4242}+\dfrac{3737}{5656}+\dfrac{3737}{7272}\right)\)

\(=18\cdot\left(\dfrac{37\cdot101}{42\cdot101}+\dfrac{37\cdot101}{56\cdot101}+\dfrac{37\cdot101}{72\cdot101}\right)\)

\(=18\cdot\left(\dfrac{37}{42}+\dfrac{37}{56}+\dfrac{37}{72}\right)\)

\(=18\cdot37\cdot\left(\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}\right)\)

\(=18\cdot37\cdot\left(\dfrac{1}{6\cdot7}+\dfrac{1}{7\cdot8}+\dfrac{1}{8\cdot9}\right)\)

\(=666\cdot\left(\dfrac{7-6}{6\cdot7}+\dfrac{8-7}{7\cdot8}+\dfrac{9-8}{8\cdot9}\right)\)

\(=666\cdot\left(\dfrac{7}{6\cdot7}-\dfrac{6}{6\cdot7}+\dfrac{8}{7\cdot8}-\dfrac{7}{7\cdot8}+\dfrac{9}{8\cdot9}-\dfrac{8}{8\cdot9}\right)\)

\(=666\cdot\left(\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}\right)\)

\(=666\cdot\left(\dfrac{1}{6}-\dfrac{1}{9}\right)\)

\(=666\cdot\dfrac{1}{18}\)

\(=37\)

a,23/99 = 23.101/99.101=2323/9999

23/99 = 23.10101/99.10101=232323/999999

b, -3737/5151=-3737.101/5151.101=-373737/515151

c, tương tự thì cứ lấy phân số đầu .2 xong rồi .4

10602

k nha!

5151+5451=10602

5151+5451=10602

k nha

hình như chưa làm đề này đâu