Final answer:
The joint density function of Y₁ and Y₂ in terms of f(X₁, X₂) is (1/2) * f(X₁, X₂).
Step-by-step explanation:
To find the joint density function of Y₁ and Y₂ in terms of f(X₁, X₂), we need to use the transformation formulas for jointly continuous random variables.
Let's start by finding the Jacobian determinant of the transformation:
|∂(Y₁, Y₂)/∂(X₁, X₂)| = |1 1| = 2
Next, we need to find the joint density function:
f(Y₁, Y₂) = f(X₁, X₂) / |∂(Y₁, Y₂)/∂(X₁, X₂)| = f(X₁, X₂) / 2
Therefore, the joint density function of Y₁ and Y₂ in terms of f(X₁, X₂) is (1/2) * f(X₁, X₂).