Directions: Simplify each algebraic expression by combining like terms.
1. 7x2 – 5x + 10x - 8x?
2.-6a3 + 5a3 + 2a? - a?
3. - 4(x + 5) – 5(x - 1)
4. -a + 5b - 6a + 5(a + 1)
5. 18x4 - 3x3 - 2x3 + x2 - 10 + 6​