\(\left(x+\dfrac{1}{3}\right)\times\dfrac{9}{14}\times\dfrac{7}{3}-\dfrac{1}{3}=1:\dfrac{9}{5}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}-\dfrac{1}{3}=\dfrac{5}{9}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}=\dfrac{5}{9}+\dfrac{1}{3}\\ \Rightarrow\left(x+\dfrac{1}{3}\right)\times\dfrac{3}{2}=\dfrac{8}{9}\\ \Rightarrow x+\dfrac{1}{3}=\dfrac{8}{9}:\dfrac{3}{2}\\ \Rightarrow x+\dfrac{1}{3}=\dfrac{16}{27}\\ \Rightarrow x=\dfrac{16}{27}-\dfrac{1}{3}\\ \Rightarrow x=\dfrac{7}{27}\)

Mình không viết lại đề nhé

a) -12x + 60 + 21 - 7x = 5

-19x = 5 - 71

-19x = -76

x = 4

b) 3 - 17 + x = 289 - 36 - 289

x = -22

\(a,-12.\left(x-5\right)+7.\left(3-x\right)=5\)

\(=.-12x+60+21-7x=5\)

\(=>-19x=5-60-21=-76\)

\(=>x=\frac{-76}{-19}=\frac{76}{19}=4\)

\(b,3-\left(17-x\right)=289-\left(36+289\right)\)

\(=>3-17+x=-36\)

\(=>x=-36+17-3=-22\)

a) -12(x-5)+7(3-x)=5

<=> -12x+60+21-7x=5

<=> 9+53x=5

<=> 53x=-4

<=> x=\(\frac{-4}{53}\)

b) 3-(17-x)=289-(36+289)

<=> 3-17+x=289-36-289

<=> -14+x=-36

<=> x=-22

 X x X : 2 = 15

x² : 2 = 15

x² = 15 x 2

x² = 30

=> x = Căn bậc 2 của 30

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

a, | x - 3/4 | = 1/2

=>\(\orbr{\begin{cases}x-\frac{3}{4}=\frac{1}{2}\\x-\frac{3}{4}=-\frac{1}{2}\end{cases}}\)

=>\(\orbr{\begin{cases}x=\frac{1}{2}+\frac{3}{4}\\x=-\frac{1}{2}+\frac{3}{4}\end{cases}}\)

=>\(\orbr{\begin{cases}x=\frac{2}{4}+\frac{3}{4}\\x=-\frac{2}{4}+\frac{3}{4}\end{cases}}\)

=>\(\orbr{\begin{cases}x=\frac{5}{4}\\x=\frac{1}{4}\end{cases}}\)

Vậy....

a) \(|x-\frac{3}{4}|=\frac{1}{2}\)

\(< =>\orbr{\begin{cases}x-\frac{3}{4}=\frac{1}{2}\\x-\frac{3}{4}=-\frac{1}{2}\end{cases}}\)

\(< =>\orbr{\begin{cases}x=\frac{1}{2}+\frac{3}{4}\\x=-\frac{1}{2}+\frac{3}{4}\end{cases}}\)

\(< =>\orbr{\begin{cases}x=\frac{5}{4}\\x=\frac{1}{4}\end{cases}}\)

Vay : x = 5/4 hoặc x =  1/4

b)\(saide\)

Sai de ban oi

3) |x(x-4)| = x

\(\Rightarrow\hept{\begin{cases}x\left(x-4\right)=x\\x\left(x-4\right)=-x\end{cases}}\Rightarrow\hept{\begin{cases}x-4=1\\x-4=-1\end{cases}}\Rightarrow\hept{\begin{cases}x=5\\x=3\end{cases}}\)

Vậy x = 3 hoặc x = 5