Quadratic equation

a x^{2} + b x + c = 0

Solutions of a quadratic equation

x_{1, 2} = \frac{- b \pm \sqrt{b^{2} - 4 a c}}{2 a}

Factors of a a quadratic equation:

a x^{2} + b x + c = a (x - x_{1}) (x - x_{2})

Vieta's formulas:

x_{1} + x_{2} = - \frac{b}{a}; x_{1} \cdot x_{2} = \frac{c}{a}

Discriminant:

D = b^{2} - 4 a c

$D > 0 \Rightarrow x_{1}, x_{2} \in ℝ$	two different real solutions
$D = 0 \Rightarrow x_{1} = x_{2} \in ℝ$	one real solution
$D < 0 \Rightarrow x_{1} = \bar{x_{2}} \in ℂ$	no real solution (two complex conjugate solutions)

Quadratic equation as a function

y = a x^{2} + b x + c

Graph of a quadratic function

Coordinates of P, vertex of the parabola:

P (- \frac{b}{2 a}, - \frac{b^{2} - 4 a c}{4 a})

Keywords:

Polynomials
Special Binomials
Progressions
Arithmetic progression
Geometric progression
Logarithm
Logarithm
Changing the base of a logarithm
Exponents
Powers
Roots
Roots
Proportionality
Direct and Inversely Proportion
Inequalities
Inequalities
Equations
Quadratic equation
Cubic Equations
Irrational and transcendental equations
Complex numbers
Complex Numbers
Adding and Subtracting Complex Numbers
Multiplying and Dividing Complex Numbers
Power of complex numbers
Roots of complex numbers
Kamatni račun
Interest calculation,
Matrices
Definition, adding & subtracting of matrices
Multiplying matrices