Answer:
Explanation:
1. 3x2 + 5x - 4 + 6x2 - x + 7
= combining like terms
= 9x2 + 4x + 3
2. 2y2 - 3y + 6 + y2 - 5y - 1 + (-4) + 2y2 - 2y
= 5y2 - 10y + 1
3. 2x2y - 3xy2 + x2y - 4x2y - 2xy2
= - x2y - 5xy2
4. x2 - y2 + 2x2 - 3xy + 4y2 + 3y2 - 5xy - x2
= 2x2 - 8xy + 6y2