Darlene wrote this proof of the identity (x + y)2 - (x - y)² = 4xy. Which of the
following is a justification for Step 5 of her proof?
Step 1: (x + y)2-(x - y)² = (x+y)(x + y) - (x-y)(x-y)
Step 2: (x+y)(x+y) - (x - y)(x - y) = (x² + xy + xy + y²) - (x² - xy - xy + y²)
Step 3: (x² + xy + xy + y²) - (x² - xy - xy + y²)(x² + 2xy + y²) - (x² - 2xy + y²)
Step 4: (x² + 2xy + ²) - (x²2²-2xy + ²) = x² + 2xy + y² - x² + 2xy-j²
Step 5: x2 + 2xy + y2-x² + 2xy-y²= 4xy