(3ײ-3y²)+(3×y-5y²+8ײ)= ???

(3ײ-3y²)+(3×y-5y²+8ײ)= 3x^2 - 3y^2 + 3xy - 5y^2 + 8x^2 = 11x^2 + 3xy - 8y^2

(3x²-3y²)+(3xy-5y²+8x²)
=3x²-3y²+3xy-5y²+8x²
=11x²-8y²+3xy