\(4x-\sqrt{8}+\dfrac{\sqrt{x^3+2x^2}}{\sqrt{x+2}}\)
\(=4x-\sqrt{8}+\dfrac{\sqrt{x^2\left(x+2\right)}}{\sqrt{x+2}}\)
\(=4x-\sqrt{8}+\dfrac{\left|x\right|\sqrt{\left(x+2\right)}}{\sqrt{x+2}}\)
\(=4x-\sqrt{8}+\left|x\right|\)
=> \(4x-\sqrt{8}+x\) khi \(x\ge0\)
\(4x-\sqrt{8}-x\) khi x < 0
=> \(5x-\sqrt{8}\) khi \(x\ge0\)
\(3x-\sqrt{8}\) khi x < 0