# Results and Formulas of Equations

• If $\alpha$ and $\beta$ are the roots of the Quadratic Equation $a{x^2} + bx + c = 0$, then

• Sum and products of the roots $\alpha$ and $\beta$ of $a{x^2} + bx + c = 0$ is given by $\alpha + \beta = - \frac{b}{a}$ and $\alpha \beta = \frac{c}{a}$
• ${b^2} - 4ac$ is called Discriminant of $a{x^2} + bx + c = 0$
• The roots of the quadratic $a{x^2} + bx + c = 0$ are
• imaginary if ${b^2} - 4ac$ is negative.
• real if ${b^2} - 4ac$ is positive or zero.
• real and equal if ${b^2} - 4ac = 0$
• real and rational if ${b^2} - 4ac \geqslant 0$ and ${b^2} - 4ac$ is a perfect square or zero.
• Real and irrational if ${b^2} - 4ac > 0$ and ${b^2} - 4ac$ is not a perfect square.
• The equation whose roots are $\alpha$ and $\beta$ (given) is given by ${x^2} - (\alpha + \beta )x + \alpha \beta = 0$
• $1$, $\omega$ and ${\omega ^2}$ where $\omega = \frac{{ - 1 + i\sqrt 3 }}{2}$ and ${\omega ^2} = \frac{{ - 1 - i\sqrt 3 }}{2}$ are called cube root of unity.
• $\omega$ and ${\omega ^2}$ are called the complex cube root of unity.
• Each of the complex cube roots of unity is the square of the other.
• The sum of the cube roots of unity is zero. i.e.,$1 + \omega + {\omega ^2} = 0$
• ${\omega ^3} = 1$
• If $\alpha$,$\beta$ and $\gamma$ are the roots of ${a_0}{x^3} + {a_1}{x^2} + {a_2}x + {a_3} = 0$ then

• If $\alpha$,$\beta$,$\gamma$ and $\delta$ are the roots of ${a_0}{x^4} + {a_1}{x^3} + {a_2}{x^2} + {a_3}x + {a_4} = 0$ then