Identify and group like terms in the expression. Like terms are terms that have the same variable raised to the same power. In this expression, group the \(x^3\) terms together, the \(x^2\) terms together, the \(x\) terms together, and the constant terms together.
Write the grouped terms explicitly: For \(x^3\) terms, combine \$5x^3$ and $-x^3$; for $x^2$ terms, combine \$3x^2$ and \$4x^2$; for $x$ terms, combine $-2x$ and \$8x$; and keep the constant term \(10\) as is.
Add or subtract the coefficients of the like terms within each group. For example, add the coefficients of the \(x^3\) terms: \(5\) and \(-1\); for the \(x^2\) terms: \(3\) and \(4\); for the \(x\) terms: \(-2\) and \(8\).
Rewrite the expression by replacing each group of like terms with their simplified form, keeping the variable and exponent intact. This will give you a simplified polynomial expression.
Double-check your simplified expression to ensure all like terms were combined correctly and that the expression is written in standard form, usually starting with the highest power of \(x\).