Question

giải pt \(\left(x-1\right)^4+\left(x+3\right)^4=40\)

Answer 1

Đặt \(x+1=t\)

PT\(\Leftrightarrow\left(t-2\right)^4+\left(t+2\right)^4=40\)

\(\Leftrightarrow\left[\left(t-2\right)^2\right]^2+\left[\left(t+2\right)^2\right]^2=40\)

\(\Leftrightarrow\left[\left(t-2\right)^2+\left(t+2\right)^2\right]^2-2\left(t-2\right)^2\left(t-2\right)^2=40\)

\(\Leftrightarrow\left(t^2-4t+4+t^2+4t+4\right)^2-2\left(t^2-4\right)^2=40\)

​\(\Leftrightarrow\left(2t^2+8\right)^2-2\left(t^2-4\right)^2=40\)​

\(\Leftrightarrow...\)