Factor: 4x^5 + 18x^3
factor out x^3 so you have 2x^3(2x^2+9) now you can solve for two values of x that would result in 0 2x^3=0 when x=0 and 2x^2+9=0 when x= pos or neg the square root(9/2)
\(4x^5 +18x^3\\ = 2x^3(2x^2) + 2x^3(9)\leftarrow \text{Take out common factors.}\\ = 2x^3(2x^2+9)\)