Thay \(2016=xyz\)vào biểu thức ta được

\(A=\frac{x^2yz}{xy+x^2yz+xyz}+\frac{y}{yz+y+xyz}+\frac{z}{xz+z+1}\)

   \(=\frac{x^2yz}{xy\left(1+xz+z\right)}+\frac{y}{y\left(z+1+xz\right)}+\frac{z}{xz+z+1}\)

   \(=\frac{xz}{xz+z+1}+\frac{1}{xz+z+1}+\frac{z}{xz+z+1}=\frac{xz+z+1}{xz+z+1}=1\)

Vậy \(A=1\)

Vì \(xyz=2016\)

\(\Rightarrow A=\frac{2016x}{xy+2016x+2016}+\frac{y}{yz+y+2016}+\frac{z}{xz+z+1}\)

\(=\frac{xyz.x}{xy+xyz.x+xyz}+\frac{y}{yz+y+xyz}+\frac{z}{xz+z+1}\)

\(=\frac{x^2yz}{xy+x^2yz+xyz}+\frac{y}{y\left(z+1+xz\right)}+\frac{z}{xz+z+1}\)

\(=\frac{x^2yz}{xy\left(1+xz+z\right)}+\frac{1}{xz+z+1}+\frac{z}{xz+z+1}\)

\(=\frac{xz}{xz+z+1}+\frac{1}{xz+z+1}+\frac{z}{xz+z+1}\)

\(=\frac{xz+1+z}{xz+z+1}=1\)

Đặt \(A=\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24\)

\(\Rightarrow A=\left(x+2\right)\left(x+5\right)\left(x+3\right)\left(x+4\right)-24\)

         \(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-24\)

Đặt \(x^2+7x+11=t\)

\(\Rightarrow A=\left(t-1\right)\left(t+1\right)-24=t^2-1-24=t^2-25=\left(t-5\right)\left(t+5\right)\)

        \(=\left(x^2+7x+11-5\right)\left(x^2+7x+11+5\right)=\left(x^2+7x+6\right)\left(x^2+7x+16\right)\)

        \(=\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)\)

\(\frac{3\left(x+1\right)}{x+2}-\frac{3x-6}{x^2-4}\)

\(=\frac{3\left(x+1\right)}{x+2}-\left(\frac{3x-6}{x^2-4}\right)\)

\(=\frac{3x^2-6x^2-12x+24}{x^3+2x^2-4x-8}\)

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

\(=\frac{3x-6}{x+2}\)

\(\frac{x^2+4x+4}{1-x}.\frac{\left(1-x\right)^2}{3\left(x+2\right)^3}\)

\(=\frac{x^2+4x+4}{1-x}.\left[\frac{\left(1-x\right)^2}{3\left(x+2\right)^3}\right]\)

\(=\frac{x^4+2x^3-3x^2-4x+4}{-3x^4-15x^3-18x^2+12x+24}\)

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

\(=\frac{-x+1}{3x+6}\)

x(x - 1) = 4x - 4

<=> x² - x = 4x - 4

<=> x² - x - 4x + 4 = 0

<=> x² - 5x + 4 = 0

<=> (x - 1)(x - 4) = 0

<=> x - 1 = 0 hoặc x - 4 = 0

<=> x = 0 + 1 hoặc x = 0 + 4

=> x = 1 hoặc x = 4

\(x\left(x-1\right)=4x-4\)\(\Leftrightarrow x\left(x-1\right)=4\left(x-1\right)\)

\(\Leftrightarrow x\left(x-1\right)-4\left(x-1\right)=0\)\(\Leftrightarrow\left(x-4\right)\left(x-1\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}x-4=0\\x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=4\\x=1\end{cases}}\)

Vậy \(x=1\)hoặc \(x=4\)

Link đây bạn tham khảo hộ

https://olm.vn/hoi-dap/detail/92924957547.html

Học tốt nhé 

cảm ơn nhé

vt sai đề nâk

từ gt=> xy+yz+xz=0

áp dụng bdt bunhia

=> A>=0

dấu= xr khi x=y=z

-> dấu = k xr

..........

hoặc: 

\(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=0\)

\(\frac{\Rightarrow1}{x^3}+\frac{1}{y^3}+\frac{1}{z^3}=\frac{3}{xyz}\)

\(\Rightarrow\frac{yz}{x^2}+\frac{xz}{y^2}+\frac{xy}{z^2}=\frac{xyz}{x^3}+\frac{xyz}{y^3}+\frac{xyz}{z^3}\)

\(\Rightarrow xyz\left(\frac{1}{x^3}+\frac{1}{y^3}+\frac{1}{z^3}\right)=xyz.\frac{3}{xyz}=3\)