\(\frac{9}{9}+\frac{9}{9}=1+1=2\)

Tích tớ nha

\(\frac{9}{9}+\frac{9}{9}=\frac{9+9}{9}=\frac{18}{9}=2\)

ủng hộ nha

a) x+ \(\frac{4}{5}\)= \(\frac{4}{5}\)+ ( \(\frac{3}{7}\)+ \(\frac{3}{5}\))

    x + \(\frac{4}{5}\)=  \(\frac{4}{5}\)+ \(\frac{36}{35}\)

    => x = \(\frac{36}{35}\)

Vậy : x = \(\frac{36}{35}\)

b) \(\frac{4}{9}\)+\(\frac{8}{9}\)+ \(\frac{12}{9}\)+ ... + \(\frac{56}{9}\)

    = \(\frac{4+8+12+...+56}{9}\)

    Ta có : 4+8+12 + ... +56

     Số các số hạng của dẫy số trên là : ( 56 -4) + 4 +1 = 14 ( số hạng )

      => Tổng trên = ( 4+56) x 14 : 2 = 420

      => \(\frac{4}{9}\)+ \(\frac{8}{9}\)+ ... + \(\frac{56}{9}\)= \(\frac{420}{9}\)= \(\frac{140}{3}\)

a)x=3/7+3/5=3x(1/7+1/5)=36/35

b)=(4+8+...+56)/9=(56+4)x14/9=280/3
 

\(\frac{9}{9}\times\frac{9}{8}\div\frac{7}{9}=1\times\frac{9}{8}\times\frac{9}{7}=\frac{9}{8}\times\frac{9}{7}=\frac{81}{56}\)

tick nha

\(\frac{9}{9}\)x\(\frac{9}{8}:\frac{7}{9}=\frac{9}{8}:\frac{7}{9}\) = \(\frac{9}{8}\) x\(\frac{9}{7}\) =\(\frac{81}{56}\)

= -4/3 nha

\(\frac{2}{9}\)+ \(\frac{-2}{9}\) x\(\frac{2}{9}\):\(\frac{14}{81}\)

= \(\left(\frac{2}{9}+\frac{-2}{9}\right)\) x \(\frac{2}{9}\): \(\frac{14}{81}\)

= 0 x \(\frac{2}{9}\): \(\frac{14}{81}\)

= 0

CHÚC BẠN HỌC TỐT

\(\frac{9}{9}+\frac{9}{9}=1\)

tíc mình nha

\(\frac{9}{9}+\frac{9}{9}=2\)

k mk mk k lại

Câu 1:\(\frac{12}{23}\times\frac{9}{28}+\frac{11}{23}\times\frac{9}{28}\)

\(=\frac{9}{28}\times\left(\frac{12}{23}+\frac{11}{23}\right)\)

\(=\frac{9}{28}\times\frac{23}{23}\)

\(=\frac{9}{28}\times1\)

\(=\frac{9}{28}\)

Câu 2:

\(3+\frac{1}{9}+\frac{3}{9}+2+\frac{5}{9}+3+2\)

\(=\left(3+2+2+3\right)+\left(\frac{1}{9}+\frac{3}{9}+\frac{5}{9}\right)\)

\(=10+\frac{9}{9}\)

\(=10+1\)

\(=11\)

\(\frac{12}{23}x\frac{9}{28}+\frac{11}{23}x\frac{9}{28}=\)\(\left(\frac{12}{23}+\frac{11}{23}\right)x\frac{9}{28}\)\(=\) \(1x\frac{9}{28}=\frac{9}{28}\)

\(3+\frac{1}{9}+\frac{3}{9}+2+\frac{5}{9}+3+2\)\(=\) \(\left(\frac{1}{9}+\frac{3}{9}+\frac{5}{9}\right)+\left(3+2+3+2\right)\)\(=\) \(1+3+2+3+2=\)\(11\) 

= \(\frac{9}{1x4}+\frac{9}{4x7}+\frac{9}{7x10}+.........+\frac{9}{19x22}+\frac{9}{22x25}\)

= \(\frac{1}{3}x\left(\frac{9}{1}-\frac{9}{4}\right)+\left(\frac{9}{4}-\frac{9}{7}\right)x\frac{1}{3}+........+\left(\frac{9}{22}-\frac{9}{25}\right)x\frac{1}{3}\)

= \(\frac{1}{3}\left(\frac{9}{1}-\frac{9}{4}+\frac{9}{4}-\frac{9}{7}+....+\frac{9}{22}-\frac{9}{25}\right)\)

= \(\frac{1}{3}x\left(\frac{9}{1}-\frac{9}{25}\right)\)

= \(\frac{1}{3}x\frac{216}{25}\)

= \(\frac{72}{25}\)

nhớ ********** nha bn thân

\(\frac{9}{4}+\frac{9}{28}+\frac{9}{70}+\frac{9}{130}+...+\frac{9}{418}+\frac{9}{550}\)

\(=3\left(\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{19.22}+\frac{3}{22.25}\right)\)

\(=3\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{22}-\frac{1}{25}\right)\)

\(=3\left(1-\frac{1}{25}\right)\)

\(=3.\frac{24}{25}=\frac{72}{25}\)

\(\frac{7}{9}+\frac{2}{9}=\frac{9}{9}=1\)

Chúc bạn học giỏi nha!!!

K cho mik vs nhé

\(\frac{7}{9}+\frac{2}{9}=\frac{9}{9}=1\)

k mik nha các bn 

trai xinh gái đẹp

dùm e đi ạ :v

đề sai e ưi

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