`9/14+19/18+19/14+35/18`

`=(9/14+19/14)+(19/18+35/18)`

`=28/14+54/18`

`=2+3`

`=5`

a, = \(\frac{11}{21}\)x \(\left(\frac{7}{4}+\frac{5}{4}\right)\)

   = \(\frac{11}{21}\)x 3

  = \(\frac{33}{21}\)

b) = \(\left(\frac{23}{14}-\frac{9}{14}\right)\)x \(\frac{6}{13}\)

    = 1 x \(\frac{6}{13}\)

    = \(\frac{6}{13}\)

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\(\frac{3}{8}.\frac{5}{7}+\frac{6}{8}.\frac{1}{14}+\frac{9}{8}.\frac{1}{21}\)

\(=\frac{3}{8}.\left(\frac{5}{7}+2.\frac{1}{14}+3.\frac{1}{21}\right)\)

\(=\frac{3}{8}.\left(\frac{5}{7}+\frac{1}{7}+\frac{1}{7}\right)\)

\(=\frac{3}{8}.1\)

\(=\frac{3}{8}\)

Làm ơn giúp mk với ai trước được thế k

a)8/3

b)1/5

bạn giải ra cho mình được k

ai giup minh bai nay voi

\(\frac{1.3.5+2.6.10+4.12.20+7.21.35}{1.5.7+2.10.14+4.20.28+7.35.49}\)

\(=\frac{1.3.5\left(1+2+4+7\right)}{1.5.7\left(1+2+7+7\right)}=\frac{1.3.5}{1.5.7}=\frac{15}{35}=\frac{3}{7}\)

\(\frac{1\cdot3\cdot5+2\cdot6\cdot10+4\cdot12\cdot20+7\cdot21\cdot35}{1\cdot5\cdot7+2\cdot10\cdot14+4\cdot20\cdot28+7\cdot35\cdot49}\)

\(=\)\(\frac{1\cdot3\cdot5\cdot\left(1+2+4+7\right)}{1\cdot5\cdot7\cdot\left(1+2+7+7\right)}\)

\(=\frac{1\cdot3\cdot5}{1\cdot5\cdot7}\)\(=\frac{15}{35}=\frac{3}{7}\)

bn vội quá viết nhầm lun kìa 

hj hj chúc bn làm bài tốt nha

cái này là 2 phép tính riêng biệt hay là gì hả bạn ?

2 phép tính khác nhau!

B. 173 + 45 + 135 + 27 + 50 

= (173+27) + (45 +135) +50

=200 + 180 + 20 + 30

= 200 +200 +30

=430

bằng 500 chứ câu a ấy

A. 35+156+21+75+179+44

=(35+75)+(156+44)+(21+179)

=100+200+200

=500

B.173+45+135+27+50

=(173+27)+(45+125)+50

=200+180+20+30

=200+200+30

=430