Function nthRoot

src/compute-engine/rubi/rubi-utils.ts:1277–1281

literal principal root u^(1/n) (Rubi NthRoot)

(u: Expression, n: number)

    u.ops.filter((t) => !t.has(x)).length === u.ops.length - 1 &&
    u.ops.some((t) => isBX(t))
  );
}

function monomialQ(u: Expression, ctx: Ctx): boolean {
  const x = ctx.x;
  if (u.symbol === x) return true;
  if (u.operator === 'Power' && u.ops)
    return u.ops[0].symbol === x && !u.ops[1].has(x);