Suppose you want to investigate the relationship between a dependent variable Y and two potential explanatory variables X₁ and X₂. Is the R² value for the equation with both X variables included necessarily at least as large as the R2 value from each equation with only a single X? Explain why or why not. Could the R2 value for the equation with both X variables included be larger than the sum of the R² values from the separate equations, each with only a single X included? Is there any intuitive explanation for this?