Quadratic Equations
Quadratic Formula
x = (-b plus or minus sqrt(b squared minus 4ac)) / 2aWhat it means: Used to solve any equation of the form ax squared + bx + c = 0. You get two answers, one with + and one with minus.
Example: Solve x squared + 5x + 6 = 0. Here a=1, b=5, c=6. x = (-5 plus or minus 1) / 2. Answer: x = -2 or x = -3
Discriminant
D = b squared minus 4acWhat it means: Tells you how many solutions exist. If D > 0: two solutions. If D = 0: one solution. If D < 0: no real solutions.
Example: For x squared + 2x + 1 = 0, D = 4 - 4 = 0. So there is exactly one solution.