A factor tree can decompose each number into factors, and then those factor are decomposed into another factors until we reach all prime factors.
In this case, we have a square root in the expression, so we will find the factors of the argument to see if we can simplify it.
The factor tree can be drawn as:
Then, we can write and simplify the expression as:
![\begin{gathered} -4\sqrt[]{98} \\ (-1)\cdot2\cdot2\cdot\sqrt[]{2}\cdot\sqrt[]{7}\cdot\sqrt[]{7} \\ -1\cdot2^2\sqrt[]{2}\cdot(\sqrt[]{7})^2 \\ -1\cdot4\sqrt[]{2}\cdot7 \\ -28\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/1i57t4p1tl7rfgr2a6ned0hkh7hu1qhe0e.png)
Answer: the simplified radical form is -28√2