Radicals and Conjugation, in Depth - Expii
Whenever you have a radical expression, like 1 + √2, there's "hidden symmetry" between that expression and its conjugates (e.g. 1 + √2 and 1 - √2 are conjugate because 2 has two square roots, +√2 and -√2). Conjugates are useful for rationalization, especially rationalizing denominators. You might see more of them when learning about complex numbers and polynomial roots.