<

=

>

5/15 < 12/8

5/15 = 3/9

5/15 > 5/8

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=

>

`12/5 =` `2``2/5`

``37/6 =` `6``1/6`

`108/9 =` `12``0/9`

a) \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)

⇔\(7\left(x-3\right)=5\left(x+5\right)\)

⇔\(7x-21=5x+25\)

⇔\(7x-21-5x-25=0\)

⇔\(2x-46=0\)

⇔\(2x=46\)

⇔\(x=23\)

b) \(\dfrac{7}{x-1}=\dfrac{x+1}{9}\)

⇔\(\left(x+1\right)\left(x-1\right)=7.9\)

⇔\(x^2-1=63\)

⇔\(x^2=64=8^2\)

⇔\(\left[{}\begin{matrix}x=8\\x=-8\end{matrix}\right.\)

\(a.\dfrac{x-3}{x+5}=\dfrac{5}{7}\)                          

    \(\left(x-3\right).7=\left(x+5\right).5\) 

    \(\left(x.7\right)+\left[\left(-3\right).7\right]=\left(x.5\right)+\left(5.5\right)\)

    \(7x-21=5x+25\)

    \(7x-5x=25+21\)

             \(2x=46\)

               \(x=46:2\)

               \(x=23\)

Câu b/ cứ làm theo câu a/ là được

AcCl₃ và NiCl₂

\(a,\dfrac{7}{12}+\dfrac{3}{4}\times\dfrac{2}{9}=\dfrac{7}{12}+\dfrac{1}{6}=\dfrac{7}{12}+\dfrac{2}{12}=\dfrac{9}{12}=\dfrac{3}{4}\)

\(b,\dfrac{8}{9}-\dfrac{4}{15}:\dfrac{2}{5}=\dfrac{8}{9}-\dfrac{4}{15}\times\dfrac{5}{2}=\dfrac{8}{9}-\dfrac{2}{3}=\dfrac{8}{9}-\dfrac{6}{9}=\dfrac{2}{9}\)

đùa thì kệ con mẹ mày xàm loz

Đáp án a là 0,75 

Đáp án b: là 0.86222222222

18/5

\(\dfrac{6}{5}:\dfrac{1}{3}=\dfrac{6}{5}\times\dfrac{3}{1}=\dfrac{18}{5}\)

\(\dfrac{6}{5}\times\dfrac{3}{1}=\dfrac{18}{5}\)

\(E=\dfrac{98:\left(\dfrac{4}{5}\cdot\dfrac{5}{4}\right)}{\dfrac{16}{25}-\dfrac{1}{25}}+\dfrac{\left(\dfrac{27}{25}-\dfrac{2}{25}\right)\cdot\dfrac{7}{4}}{\left(\dfrac{59}{9}-\dfrac{13}{4}\right)\cdot\dfrac{36}{17}}\\ E=\dfrac{98}{\dfrac{3}{5}}+\dfrac{\dfrac{7}{4}}{\dfrac{119}{36}\cdot\dfrac{36}{17}}\\ E=\dfrac{490}{3}+\dfrac{\dfrac{7}{4}}{7}=\dfrac{490}{3}+\dfrac{1}{4}=\dfrac{1963}{12}\)

`9/14 : 3/7 + 5/6 = 3/98 + 5/6 = 127/147`

__________________

`4/7 xx (4 - 7/3) = 4/7 xx 5/3 = 20/21`

\(\dfrac{9}{14}:\dfrac{3}{7}+\dfrac{5}{6}=\dfrac{9}{14}\times\dfrac{7}{3}+\dfrac{5}{6}=\dfrac{3}{2}+\dfrac{5}{6}=\dfrac{7}{3}\)

\(\dfrac{4}{7}\times\left(4-\dfrac{7}{3}\right)=\dfrac{4}{7}\times\dfrac{5}{3}=\dfrac{20}{21}\)

\(=\dfrac{3\times3}{2\times7}\times\dfrac{7}{3}+\dfrac{5}{6}=\dfrac{3}{2}+\dfrac{5}{6}=\dfrac{9}{6}+\dfrac{5}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)

b)\(=\dfrac{4}{7}\times\dfrac{5}{3}=\dfrac{20}{21}\)

mình không có tìm thấy ô trống đâu

 mong mọi người thông cảm

a)S                        b)Đ                       c)S                                d)Đ

a) \(\dfrac{7}{9}>\dfrac{7}{8}\rightarrow Sai\)

b) \(\dfrac{3}{5}=\dfrac{21}{35}< \dfrac{5}{7}=\dfrac{25}{35}\rightarrowĐúng\)

c) \(\dfrac{111}{112}=\dfrac{112}{113}\left(\dfrac{111}{112}< \dfrac{112}{113}\right)\rightarrow Sai\)

\(\dfrac{13}{9}=\dfrac{91}{81}< \dfrac{117}{81}\rightarrow Sai\)