Answer:
2
Step-by-step explanation:
We are asked to perform the subtraction
x² + xy - 3y² - (5x² - xy + y²) ← distribute the parenthesis by - 1
= x² + xy - 3y² - 5x² + xy - y² ← collect like terms
= (x² - 5x²) + (xy + xy) + (- 3y² - y² )
= - 4x² + 2xy - 4y²
