\(\frac{2}{5}-\frac{1}{2}\left(x+\frac{1}{3}\right)=\frac{7}{5}\)

\(\frac{1}{2}\left(x+\frac{1}{3}\right)=\frac{2}{5}-\frac{7}{5}\)

\(\frac{1}{2}\left(x+\frac{1}{3}\right)=-1\)

\(x+\frac{1}{3}=-1:\frac{1}{2}\)

\(x+\frac{1}{3}=-2\)

\(x=-2-\frac{1}{3}\)

\(x=-\frac{7}{3}\)

\(\frac{2}{5}-\frac{1}{2}.\left(x+\frac{1}{3}\right)=\frac{7}{5}\)

\(\Rightarrow\frac{1}{2}.\left(x+\frac{1}{3}\right)=\frac{2}{5}-\frac{7}{5}\)

\(\Rightarrow\frac{1}{2}.\left(x+\frac{1}{3}\right)=-1\)

\(\Rightarrow x+\frac{1}{3}=-2\)

\(\Rightarrow x=-\frac{7}{3}\)

(\(\dfrac{2}{3}\) + \(\dfrac{8}{9}\) + \(\dfrac{26}{27}\) + \(\dfrac{80}{81}\) + \(\dfrac{242}{243}\)) : y = 5

Đăt      A = \(\dfrac{2}{3}\) + \(\dfrac{8}{9}\) + \(\dfrac{26}{27}\) + \(\dfrac{80}{81}\) + \(\dfrac{242}{243}\) 

          3A =  2 + \(\dfrac{8}{3}\) + \(\dfrac{26}{9}\) + \(\dfrac{80}{27}\) + \(\dfrac{242}{81}\) 

      3A - A = 2 + \(\dfrac{8}{3}\) + \(\dfrac{26}{9}\) + \(\dfrac{80}{27}\) + \(\dfrac{242}{81}\) - \(\dfrac{2}{3}\)-\(\dfrac{8}{9}\)-\(\dfrac{26}{27}\)-\(\dfrac{80}{81}\)-\(\dfrac{242}{243}\)

       A x (3 - 1) = 2 - \(\dfrac{242}{243}\)+ (\(\dfrac{8}{3}\) - \(\dfrac{2}{3}\))+(\(\dfrac{26}{9}\) - \(\dfrac{8}{9}\))+(\(\dfrac{80}{27}\)-\(\dfrac{26}{27}\))+(\(\dfrac{242}{81}\)-\(\dfrac{80}{81}\))-\(\dfrac{242}{243}\)

      A x 2 = 2 - \(\dfrac{242}{243}\) + 2 + 2 + 2 + 2

     A  x 2 = (2 + 2 + 2  +2 + 2) - \(\dfrac{242}{243}\)

    A  x 2 =  2x5 - \(\dfrac{242}{243}\)

   A  x 2 = 10 - \(\dfrac{242}{243}\)

   A x 2 = \(\dfrac{2188}{243}\)

   A = \(\dfrac{2188}{243}\) : 2

A = \(\dfrac{1094}{243}\)

\(\dfrac{1094}{243}\) : y = 5

  y = \(\dfrac{1094}{243}\) : 5

  y =  \(\dfrac{1094}{1215}\)

1200-31/40=47969/40

câu 2 =45/56+25/56=(45+25)/56=70/56=5/4

Bài 1 

a, Có thể lập xy=21 <=> x=3;y=7 hoặc x=-3;y=-7

                                <=> x=7;y=3 hoặc x=-7;y=-3  ....v..v...

b, \(\left(x+5\right)\left(y-3\right)=15\)

\(\Rightarrow\orbr{\begin{cases}x+5=15\\y-3=15\end{cases}\Rightarrow\orbr{\begin{cases}x=10\\y=18\end{cases}}}\)

c, \(\left(2x-1\right)\left(y-3\right)=12\)

\(\Rightarrow\orbr{\begin{cases}2x-1=12\\y-3=12\end{cases}\Rightarrow\orbr{\begin{cases}2x=13\\y=15\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{13}{2}\\y=15\end{cases}}}\)

Bài 2 

Ư(6)={1;2;3;6} => 1+2+3+6=12

Ư(8)={1;2;4;8} => 1+2+4+8 =15

=> Tổng 2 ước này đều \(⋮3\)

๖²⁴ʱミ★Šїℓεŋէ❄Bʉℓℓ★彡⁀ᶦᵈᵒᶫ  mù mắt =)) t làm mẫu câu b thôi, c nhìn vào mà làm

b) \(\left(x+5\right)\left(y-3\right)=15\)

\(\Rightarrow y-3=\frac{15}{x+5}\Rightarrow y=3+\frac{15}{x+5}\)

\(\Rightarrow x+5\inƯ\left(15\right)\)

Ta có: \(Ư\left(15\right)=\left\{-15;-5;-3;-1;0;1;3;5;15\right\}\)

\(x=\left\{0;-10;-8;-6;-20;-4;-2;0;10\right\}\)
Vì \(x\inℕ\Rightarrow x=\left\{0;10\right\}\)
\(\Rightarrow y=\left\{6;4\right\}\)

Vậy: (x,y) = {(0;10); (6;4)}

a,x=3,y=7

b,x=0,y=6

mẫu số chung giữa 6 với 13 là nhiêu vậy mấy bạn

drom room có nghĩa sang tiếng việt là phòng ngủ tập thể

chúc

bạn

hok

tốt

nhé

nhớ

k

cho

mình

nha

phòng ngủ tập thể

k mình đi

a,0,12 x 300 = 36

b, 4,5 x 2,5  + 4,5 x 4,5 + 2,5 + 4,5 x 2 + 2

=  4,5 x 2,5  + 4,5 x 4,5 + 4,5 x 2 + (2,5 +2)

= 4,5 x 2,5  + 4,5 x 4,5 + 4,5 x 2  + 4,5

= 4,5 x 2,5 + 4,5 x 4,5 + 4,5 x 2 + 4,5 x 1 

= 4,5 x ( 2,5 + 4,5 + 2 + 1)

= 4,5 x ( 7 + 3)

= 4,5 x 10

= 45

\(a.0,12\times300\\ =0,12\times100\times3\\ =12\times3\\ =36\\ b.4,5\times2,5+4,5\times4,5+2,5+4,5\times2+2\\=4,5\times2,5+4,5\times4,5+4,5\times2+\left(2,5+2\right)\\ =4,5\times2,5+4,5\times4,5+4,5\times2+4,5\\ =4,5\times\left(2,5+4,5+2+1\right)\\ =4,5\times\left(7+3\right)\\ =4,5\times10\\ =45\)

#1q2w3e

A\(\frac{7}{8}+\frac{7}{12}+\frac{9}{8}+\frac{5}{12}\)

\(=\left(\frac{7}{12}+\frac{5}{12}\right)+\left(\frac{7}{8}+\frac{9}{8}\right)\)

\(=1+2\)

\(=3\)