Chapter 4 - Polynomials - 4.4 Addition and Subtraction of Polynomials - 4.4 Exercise Set - Page 259: 22

$4x^5+3x^4+9x^2-8x+1$

By combining like terms, the given expression, $ (4x^5-6x^3-9x+1)+(3x^4+6x^3+9x^2+x) $, simplifies to \begin{array}{l} 4x^5+3x^4+(-6x^3+6x^3)+9x^2+(-9x+x)+1 \\\\= 4x^5+3x^4+0x^3+9x^2-8x+1 \\\\= 4x^5+3x^4+9x^2-8x+1 .\end{array}