Answer:
Multiply by

Explanation:
Moving from x‐³ to x¹ requires an increase in the index of the variable. This can be done by multiplying like variables together thus adding the indices.
Multiplying any 2 like terms, is just as good as adding the indices of the the two terms while maintaining a single base. For example:

Similarly:

NB: THIS CAN ONLY BE DONE WHEN THERE ARE LIKE TERMS OR SIMILAR BASES.
Therfore to find how many x's you need to multiply by to move from x-³ to x¹ is just as good as saying:

{where a represents the index of the variable}

therfore the index of the variable will be 4.
x⁴
Thus you have to multiply x-³ by x four times to get to x¹ which is simply the same as Multiplying by
