The first thing we need to know is that taking the square root of a negative number will result in needing to apply the following rule:
1. The negative sign will turn into an i. This is placed outside of the square root.
2. This results in the following:
![\sqrt[]{-15}=i\sqrt[]{15}](https://img.qammunity.org/2023/formulas/mathematics/college/4m5xl132h08ibh0hocbwygvzznocgqfimi.png)
Then, we will multiply this by the square root of 5:
![i\sqrt[]{15}*\sqrt[]{5}](https://img.qammunity.org/2023/formulas/mathematics/college/54w5r69tzn16lsmxmgd4ksc7ppx0z9hprs.png)
This can be rationalized:
We can take a 5 out of the 15, leaving a 3. This will also cancel the square root of 5.
![5i\sqrt[]{3}](https://img.qammunity.org/2023/formulas/mathematics/college/nn24hclo11k815yzkyf6uv2xvofoy8f64q.png)
Therefore, this leaves us with our final answer.