1. The problem involves finding the roots $x_2$, $x_3$, and $x_4$ of a polynomial or equation where you already have $x_2 = 1.348$. 2. To find $x_3$ and $x_4$, you typically use methods such as factoring, synthetic division, or the quadratic formula if the polynomial degree is 4 and you have partial roots. 3. If the polynomial is quartic, after finding $x_2$, divide the polynomial by $(x - x_2)$ to reduce it to a cubic. 4. Then, find the roots of the cubic either by factoring or using the cubic formula. 5. Continue this process until all roots $x_3$ and $x_4$ are found. 6. Without the original polynomial or equation, exact values for $x_3$ and $x_4$ cannot be determined here. 7. Please provide the original equation or polynomial for precise calculation of $x_3$ and $x_4$.