\(=x^2-6x+8-x^2+2x-1=-4x+7\)

x/x           =  12/1 +5/1

x/x           = 3/4 - 17/1 

x/x           =  -65/4

a.X x 5 + X x4 = 36

X (5+4) = 36 

X = 4

b. X x 4 - X x3 =  18

X (4-3) = 18

X = 18

X :0,2 + x X 4=36

X :2/10+x x 4=36

x x10/2+x x 4 =36

x x5 + x x4 =36

x x (4+5)=36

x x 9 =36

x=36:9

x=4

x :0.25 - x x 3 =18

x:25/100- x x 3=18 

x x100/25- x x 3=18

x x 4- x x 3 =18

x x(4-3)=18

x x 1=18

x=18:1

x=18

\(\left(-x-2\right)^2+\left(x-2\right)\left(x^2+2x+4\right)-x^2\left(x-6\right)\)

\(=-x^3-6x^2-12x-8+x^3-8-x^3+6x^2\)

\(=-x^3-12x-16\)

\(\dfrac{3}{2}\)(\(x\) - \(\dfrac{5}{3}\)) - \(\dfrac{4}{5}\) = \(x\) + 1

\(\dfrac{3}{2}\) \(x\) - \(\dfrac{15}{6}\) - \(\dfrac{4}{5}\) = \(x\) + 1

\(\dfrac{3}{2}\)\(x\) - \(x\)          = 1 + \(\dfrac{15}{6}\) + \(\dfrac{4}{5}\)

\(\dfrac{1}{2}\)\(x\)                 =\(\dfrac{43}{10}\)

    \(x\)                 = \(\dfrac{43}{10}\) \(\times\) 2

     \(x\)                = \(\dfrac{43}{5}\)

\(\dfrac{3}{2}\left(x-\dfrac{5}{3}\right)-\dfrac{4}{5}=x+1\\ \Rightarrow\dfrac{3.\left(x-\dfrac{5}{3}\right)}{2}-\dfrac{4}{5}=x+1\\ \Rightarrow\dfrac{3x-5}{2}-\dfrac{4}{5}=x+1\Rightarrow\dfrac{5\left(3x-5\right)}{10}-\dfrac{8}{10}=x+1\\ \Rightarrow\dfrac{15x-33}{10}=x+1\\ \Rightarrow\dfrac{15x-33}{10}-x=x+1\\ \Rightarrow\dfrac{15x-33}{10}=x+1-x\\ \Rightarrow5x-33=10\\ \Rightarrow5x=10+33\\\Rightarrow5x=43\\ \Rightarrow x=\dfrac{43}{5} \)

\(\dfrac{3}{2}\times\left(x-\dfrac{5}{3}\right)-\dfrac{4}{5}=x+1\)

\(\Leftrightarrow\dfrac{3}{2}\times x-\dfrac{5}{2}-\dfrac{4}{5}=x+1\)

\(\Leftrightarrow\dfrac{3}{2}\times x-x=1+\dfrac{5}{2}+\dfrac{4}{5}\)

\(\Leftrightarrow\dfrac{1}{2}\times x=\dfrac{43}{10}\)

\(\Leftrightarrow x=\dfrac{43}{10}\div\dfrac{1}{2}\)

\(\Leftrightarrow x=\dfrac{43}{5}\)

\(\Leftrightarrow\dfrac{2\left(x+2\right)-8x+24-1+x}{8}=0\)

\(\Leftrightarrow2x+4-8x+24-1+x=0\)

\(\Leftrightarrow-5x+27=0\)

\(\Leftrightarrow x=\dfrac{27}{5}\)

MÌNH CẦN GẤP LẮMMMM ĐÓOOOO

MỌI NGƯỜI GIẢI CHI TIẾT ĐỪNG BỎ BƯỚC NÀO NHAAAAA, MÌNH CẦN GẤP THIỆT ÁAAAA

\(3\left(x-2\right)^2=x^2-4\)

\(\Leftrightarrow3\left(x-2\right)^2-\left(x-2\right)\left(x+2\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(3x-6-x-2\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(2x-8\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(x-4\right)=0\)

\(\Leftrightarrow x-2=0\) hay \(x-4=0\)

\(\Leftrightarrow x=2\) hay \(x=4\)

-Vậy \(S=\left\{2;4\right\}\)