Chapter 4 - Polynomials - 4.4 Addition and Subtraction of Polynomials - 4.4 Exercise Set - Page 260: 46

$x$

Removing the grouping symbols, then the given expression, $ (8x^5+3x^4+x-1)-(8x^5+3x^4-1) $, is equivalent to \begin{array}{l} 8x^5+3x^4+x-1-8x^5-3x^4+1 .\end{array} By combining like terms, then \begin{array}{l} (8x^5-8x^5)+(3x^4-3x^4)+x+(-1+1) \\\\= 0x^5+0x^4+x+0 \\\\= x .\end{array}