a: \(\left(x+2\right)\left(x^2-2x+4\right)-x\left(x-1\right)\left(x+1\right)+3x=2\)
=>\(x^3+8-x\left(x^2-1\right)+3x=2\)
=>\(x^3+8-x^3+x+3x=2\)
=>4x=2-8=-6
=>\(x=-\frac64=-\frac32\)
b: \(2x^3-50x=0\)
=>\(2x\left(x^2-25\right)=0\)
=>x(x-5)(x+5)=0
=>x∈{0;5;-5}
c: \(5x^2-4\left(x^2-2x+1\right)-5=0\)
=>\(5x^2-4x^2+8x-4-5=0\)
=>\(x^2+8x-9=0\)
=>(x+9)(x-1)=0
=>\(\left[\begin{array}{l}x+9=0\\ x-1=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=-9\\ x=1\end{array}\right.\)
d: \(x^3-5x^2+8x-4=0\)
=>\(x^3-x^2-4x^2+4x+4x-4=0\)
=>\(\left(x-1\right)\left(x^2-4x+4\right)=0\)
=>\(\left(x-1\right)\left(x-2\right)^2=0\)
=>\(\left[\begin{array}{l}x-1=0\\ x-2=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=1\\ x=2\end{array}\right.\)
