Question

x²(x-5)-4x+20=0

Answer 1

\(x^2\left(x-5\right)-4x+20=0\\ \Leftrightarrow x^2\left(x-5\right)-4\left(x-5\right)=0\\ \Leftrightarrow\left(x-5\right)\left(x^2-4\right)=0\\ \Leftrightarrow\left(x-5\right)\left(x+2\right)\left(x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\\x=2\end{matrix}\right.\)