Answer: Partitioning formula
Explanation:
This formula is the formula that can be used to find the coordinates of a given point that partitions a line segment into ratio k. Therefore, it is the partitioning formula.
*Note: It may be partition or partitioning, but I'm not entirely sure which form of the verb will be asked for. The partition(ing) formula is sometimes also called the section(ing) formula, so that may be the answer as well, but since it's a fill-in-the-blank, I don't know which one will be asked for. Whichever term you have learned in school lately is probably the right one, but I don't know what you've learned. I looked at some other questions you have asked on your profile, and partitioning was an answer choice on some of them, so I believe that partitioning is the correct answer here.
I hope this helps!