a: \(=\dfrac{7}{5}\cdot\dfrac{15}{49}-\dfrac{12+10}{15}:\dfrac{11}{5}\)

\(=\dfrac{3}{7}-\dfrac{22}{15}\cdot\dfrac{5}{11}=\dfrac{3}{7}-\dfrac{2}{3}=\dfrac{9-14}{21}=\dfrac{-5}{21}\)

b: =>2,8x-32=-60

=>2,8x=-28

hay x=-10

a) x=-10

b)x=2

a,    x=10

b,   x= 2

A/\(\left(2,8x-32\right):\frac{2}{3}=-90\)

\(\left(\frac{28}{10}x-32\right)=\frac{-90}{1}.\frac{2}{3}\)

\(\left(\frac{14}{5}x-32\right)=\frac{-30}{1}.\frac{2}{1}\)

\(\left(\frac{14}{5}x-32\right)=-60\)

\(\frac{14}{5}x=-60+32\)

\(\frac{14}{5}x=-28\)

\(x=\frac{-28}{1}:\frac{14}{5}\)

\(x=\frac{-28}{1}.\frac{5}{14}\)

\(x=\frac{-2}{1}.\frac{5}{1}=-10\)

B/\(\left(4,5-2x\right).1\frac{4}{7}=\frac{11}{14}\)

\(\left(\frac{45}{10}-2x\right).\frac{11}{7}=\frac{11}{14}\)

\(\left(\frac{9}{2}-2x\right)=\frac{11}{14}:\frac{11}{7}\)

\(\left(\frac{9}{2}-2x\right)=\frac{11}{14}.\frac{7}{11}\)

\(\left(\frac{9}{2}-2x\right)=\frac{1}{2}.\frac{1}{1}=\frac{1}{2}\)

\(2x=\frac{9}{2}-\frac{1}{2}\)

\(2x=\frac{8}{2}\)

\(x=\frac{8}{2}:\frac{2}{1}=\frac{8}{2}.\frac{1}{2}\)

\(x=\frac{4}{2}.\frac{1}{1}=\frac{4}{2}=2\)

Em thích

a) | x + 12 - 41| = 11

\(\Rightarrow\orbr{\begin{cases}x+12-41=11\\x+12-41=-11\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=40\\x=18\end{cases}}\)

Vậy \(x\in\left\{40;18\right\}\)

À ... cái "Em thích" kia là đánh nhầm ạ :33

Xin các bạn đừng để ý :v

a) \(\left|x+12-41\right|=11\)

\(\Rightarrow x+12-41=11\)hoặc \(x+12-41=-11\)

Với x + 12 - 41 = 11

     x + 12 = 11 + 41

     x + 12 = 52

     x = 52 - 12

    x = 40

Với x + 12 - 41 = -11

      x + 12 = -11 + 41

      x + 12 = 30

      x = 30 - 12

      x = 18

=> x = 40 hoặc 18

Vậy \(x\in\left\{40;18\right\}\)

a ) (2,8x - 32 ) : 2/3 = -90 

<=> 2,8x -32 = -60

<=> 2,8x = -28

<=> x = -10 

b ) 4/5 + 5/7 :x =1/6

<=> 5/7:x = -19/30

<=> x = -150/133

a)\(\left(2,8x-32\right):\frac{2}{3}=-90\)

\(2,8x-32=-90\cdot\frac{2}{3}\)

\(2,8x-32=-60\)

\(2,8x=-60+32\)

\(2,8x=-28\)

\(x=-28:2,8\)

\(x=-10\)

Vậy x = -10

b) \(\frac{4}{5}+\frac{5}{7}:x=\frac{1}{6}\)

\(\frac{5}{7}:x=\frac{1}{6}-\frac{4}{5}\)

\(\frac{5}{7}:x=\frac{-19}{30}\)

\(x=\frac{5}{7}:\frac{-19}{30}\)

\(x=\frac{-150}{133}\)

Vậy x = -150/133

=))

\(xy+x+y=4\)

\(\Leftrightarrow xy+x+y+1=4+1\)

\(\Leftrightarrow x\left(y+1\right)+\left(y+1\right)=5\)

\(\Leftrightarrow\left(x+1\right)\left(y+1\right)=5\)

\(\Leftrightarrow x+1;y+1\inƯ\left(5\right)\)

\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x+1=1\\y+1=5\end{matrix}\right.\\\left\{{}\begin{matrix}x+1=5\\y+1=1\end{matrix}\right.\\\left\{{}\begin{matrix}x+1=-1\\y+1=-5\end{matrix}\right.\\\left\{{}\begin{matrix}x+1-5\\y+1=-1\end{matrix}\right.\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x=0\\y=4\end{matrix}\right.\\\left\{{}\begin{matrix}x=4\\y=0\end{matrix}\right.\\\left\{{}\begin{matrix}x=-2\\y=-6\end{matrix}\right.\\\left\{{}\begin{matrix}x=-6\\y=-2\end{matrix}\right.\end{matrix}\right.\)

Vậy ...

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

hàm số f(x) có giá trị ngyên \(\Leftrightarrow\) 5 \(⋮\)x-2

hay x-2 là các ước của 5

nên x-2\(\in\){-5;-1;1;5}

Vậy x\(\in\){-3;1;3;7}

Đó là đáp số cho bài toán của bạn