Exponent

Exponent[expr, form] gives the maximum power with which form appears in the expanded form of expr.

Examples

Find highest power of x:

Exponent[x^3 + 2x^2 + 5x + 1, x]
(* 3 *)

Exponent in a product:

Exponent[x^2 * (1 + x)^3, x]
(* 5 *)

Please visit the official Wolfram Language Reference for more details.