Quadratic functions — A/L Combined Mathematics

A. Imaginary Unit and Complex Numbers Definition: A complex number is a number of the form z = a + ib, where a and b are real numbers, and i is the imaginary unit defined by i² = -1. Explanation: Real numbers alone are insufficient to solve equations like x² + 1 = 0. The imaginary unit 'i' was introduced to provide a solution, where i = √(-1). A complex number combines a real part (a) and an imaginary part (b) multiplied by 'i', extending the number system to include solutions for all polynomial equations. Think of it as: Think of complex numbers like coordinates on a map. Instead of just moving left/right (real numbers), you can also move up/down (imaginary numbers), allowing you to reach any point on the map. Real-world application: Complex numbers are crucial in electrical engineering (analyzing AC circuits), signal processing, quantum mechanics, and fluid dynamics. For instance, in AC circuits, voltage and current are represented as complex numbers to easily handle phase differences and impedance calculations. B.