31.1.4 When Complex Numbers Are Equal, and How We Sort Them
Core ideaPicture this: two ID cards count as the same person only when both real part and imaginary part match; b=0 makes it a real number, a=0 makes it purely imaginary
Module goal. Picking up the coordinate geometry from the last stage, we start from a genuine dead end — the real number line just isn't enough — and from there introduce the imaginary unit and the idea of complex numbers