A quadratic equation is a second order (the highest power of the variable is 2) polynomial equation of 1 variable. It is typically written either as $y = ax^2 + bx +c$ or $y = a(x+k)^2 +c$ When graphed, it forms a parabola, with a single vertex (maximum or minimum point) and 0, 1, or 2 real roots (points where the graph crosses the x axis). In real life, we find this equation when dealing with ballistics, engineering, and optics. It also turns up in economics.
