please explain this

Consider the following scenario. You want to look at the independent relationship between X1 and Y, accounting for a third variable X2. X2 has a strong relationship with Y, but little or no relationship with X1. What technique would you use to examine the relationship? Explain, using the concepts discussed in class, what would happen to the independent relationship between X1 and Y. If you like, upload a diagram or provide an actual example to explain