1

x + 7/12= 15/18

x= 15/18-7/12

x= 1/4

k mk nhé

3

4/10= 2/5

\(\frac{x}{15}\)=\(\frac{2}{5}\)

x= 15:5x2= 6

x= 6

k mk nhé

a) Để \(\frac{-3}{x-1}\in Z\) \(\Leftrightarrow-3⋮\left(x-1\right)\)

   \(\Rightarrow x-1\inƯ\left(-3\right)=\left\{-1;1;-3;3\right\}\)

   \(\Rightarrow x=\left\{2;0;4;-2\right\}\)

b) Để \(\frac{-4}{2x-1}\in Z\Leftrightarrow-4⋮\left(2x-1\right)\)

\(\Rightarrow2x-1\inƯ\left(-4\right)=\left\{-1;1;-2;2;-4;4\right\}\)

\(\Rightarrow2x=\left\{0;2;-1;3;-3;5\right\}\)

\(\Rightarrow x=\left\{0;1;\frac{-1}{2};\frac{3}{2};\frac{-3}{2};\frac{5}{2}\right\}\)

Mà \(x\in Z\) \(\Rightarrow x=\left\{0;2\right\}\)

c) \(\frac{3x+7}{x-1}=\frac{3\left(x-1\right)+10}{x-1}\)

Vì \(3\left(x-1\right)⋮\left(x-1\right)\Rightarrow10⋮\left(x-1\right)\)

\(\Rightarrow x-1\inƯ\left(10\right)=\left\{1;-1;2;-2;5;-5;10;-10\right\}\)

\(\Rightarrow x=\left\{2;0;3;-1;6;-4;11;-9\right\}\)

d) Tương tự

a,x(4;-2;2;0)

a) \(\frac{-3}{x-1}\Rightarrow\frac{-3}{x-1}=-3\)để x nguyên

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

\(\Rightarrow x=2\)

b)\(\frac{-4}{2x-1}=-4\)để x nguyên

\(\frac{-4}{1}=-4\Rightarrow\frac{-4}{\left(1+1\right)\div2}=x=1\)

\(\Rightarrow x=1\)

c) \(\frac{3x+7}{x-1}=5\)để x nguyên 

\(\frac{25}{5}=5\Rightarrow\frac{\left(25-7\right)\div3}{5+1}=x=6\)

\(\Rightarrow x=6\)

 d) \(\frac{4x-1}{3-x}=7\)để x nguyên

\(\frac{7}{1}=7\Rightarrow\frac{\left(7+1\right)\div4}{3-1}=x=2\)

\(\Rightarrow x=2\)

để các phân số sao là số nguyên thì mẫu phải là ước của tử 

dựa vào đây rồi em tự làm nhé , chị ngại làm lắm

vâng cảm ơn chị em sẽ thử !

a) Để \(\frac{3}{x-1}\inℤ\Rightarrow\left(x-1\right)\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)

\(\Rightarrow x\in\left\{-2;0;2;4\right\}\)

b) Để \(\frac{4}{2x-1}\inℤ\Rightarrow\left(2x-1\right)\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\)

=> \(2x\in\left\{-3;-1;0;2;3;5\right\}\)

=> \(x\in\left\{-\frac{3}{2};-\frac{1}{2};0;1;\frac{3}{2};\frac{5}{2}\right\}\)

c) Ta có: \(\frac{3x+7}{x-7}=\frac{\left(3x-21\right)+28}{x-7}=2+\frac{28}{x-7}\)

Xong xét các TH như a,b nhé

thanks nhưng mai mik mới t.i.k đc bạn

-4/8 nha các bạn

Câu 1:

\(-\frac48\) = \(\frac{x}{10}\) = - \(\frac{7}{y}\) = \(\frac{z}{-24}\)

- \(\frac48\) = \(\frac{x}{10}\) ⇒ \(x\) = - \(\frac48\) x 10 = -5

\(\frac{-4}{8}\) = \(\frac{-7}{y}\) ⇒ y = -7 : ( \(-\frac48\)) = - 7 x (-8/4) = 14

\(-\frac48\) = \(\frac{z}{-24}\) ⇒ z = - \(\frac48\) x (-24) = 12

Vậy (x; y; z)= (-5; 14; 12)