\(B=\frac{2x}{y+z+t}-\frac{3y}{x+z+t}+\frac{4z}{x+y+t}-\frac{5t}{x+y+z}\)

\(B=\frac{2x}{-x}-\frac{3y}{-y}+\frac{4z}{-z}-\frac{5t}{-t}\)

\(B=-2+3-4+5=2\)

giải chi tiết hơn giùm mình dc ko

\(B=\frac{2x}{x+y+z+t-x}-\frac{3y}{x+y+z+t-y}+\frac{4z}{y+z+t+x-z}-\frac{5t}{x+y+z+t-t}\)

Thay x+y+z+t =0.Ta có

\(B=\frac{2x}{-x}-\frac{3y}{-y}+\frac{4z}{-z}-\frac{5t}{-t}=-2+3-4+5\)

B=2

\(\frac{x}{y+z+t}=\frac{y}{z+t+x}=\frac{z}{t+x+y}=\frac{t}{x+y+z}\)

\(\Leftrightarrow1+\frac{y+z+t}{x}=1+\frac{z+t+x}{y}=1+\frac{t+x+y}{z}=1+\frac{x+y+z}{t}\)

\(\Leftrightarrow\frac{x+y+z+t}{x}=\frac{x+y+z+t}{y}=\frac{x+y+z+t}{z}=\frac{x+y+z+t}{t}\)

\(TH1:x+y+z+t=0\left(ĐK:x,y,z,t\ne0\right)\)

\(\Rightarrow\hept{\begin{cases}x+y=-\left(z+t\right)\\y+z=-\left(x+t\right)\end{cases}\Rightarrow P=\frac{-\left(z+t\right)}{z+t}+\frac{-\left(x+t\right)}{x+t}+\frac{z+t}{-\left(z+t\right)}+\frac{t+x}{-\left(y+z\right)}}\)=-4

\(TH2:x+y+z+t\ne0\)

\(\Rightarrow x=y=z=t\Rightarrow P=\frac{x+x}{x+x}+\frac{x+x}{x+x}+\frac{x+x}{x+x}+\frac{x+x}{x+x}=4\)

Vậy P=4 hay P=-4

Trả lời :..................................

P = 4,..................................

Hk tốt......................................

eheheeheheheheh deex

Ta có : \(\frac{x+y+z-3t}{t}=\frac{y+z+t-3x}{x}=\frac{z+t+x-3y}{y}=\frac{t+x+y-3z}{z}\)

=> \(\frac{x+y+z-3t}{t}+4=\frac{y+z+t-3x}{x}+4=\frac{x+z+t-3y}{y}+4=\frac{x+y+t-3z}{z}+4\)

=> \(\frac{x+y+z+t}{t}=\frac{x+y+z+t}{x}=\frac{x+y+z+t}{y}=\frac{x+y+z+t}{z}\)

=> \(\frac{2012}{x}=\frac{2012}{y}=\frac{2012}{z}=\frac{2012}{t}=\frac{2012+2012+2012+2012}{x+y+z+t}=\frac{2012.4}{2012}=4\)

=> x = y = z = t = 403

Khi đó A = x + 2y - 3z + t

              = x + 2x - 3x + x

             = x = 403

Vậy x = 403 

=y+z+t/x - n.x/x=z+t+x/y - n.y/y=t+x+y/z - n.z/z=x+y+z/t - n.t/t

=y+z+t/x - n=z+t+x/y - n=t+x+y/z - n=x+y+z/t - n

=y+z+t/x=z+t+x/y=t+x+y/z=x+y+z/t

áp dụng tính chất của dãy tỉ số bằng nhau ta có:

y+z+t/x=z+t+x/y=t+x+y/z=x+y+z/t=y+z+t+z+t+x+t+x+y+x+y+z/x+y+z+t=3.(x+y+z+t)/x+y+z+t=3

ok bạn tiếp tục làm được nhé cho mih nha

7a5 ddieemr danh

\(\frac{x}{y+z+t}=\frac{y}{z+t+x}=\frac{z}{t+x+y}=\frac{t}{x+y+z}\)

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

\(\frac{x+y+z+t}{y+z+t}=\frac{y+z+t+x}{z+t+x}=\frac{z+t+x+y}{t+x+y}=\frac{t+x+y+z}{x+y+z}\)

Khi đó \(P=1+1+1+1=4\)

Khi đó \(P=\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)=-4\)

ms đúng \(\frac{x}{y+z+t}=\frac{y}{z+t+x}=\frac{z}{t+x+y}=\frac{t}{x+y+z}\)