Chapter 3 : Quadratic Equations and Complex Numbers

Completing the square

To add a term c to an expression of the form x2 + bx such that ax2 + bx + c is a perfect square trinomial.

Complex number

A number written in the form a + bi, where a and b are real numbers.

Discriminant

The expression b2 - 4ac in the Quadratic Formula.

Imaginary number

A number written in the form a + bi, where a and b are real numbers and b is not zero.

Imaginary unit, i

The square root of -1.

Pure imaginary number

A number written in the form a + bi, where a =0 and b is not zero.

Quadratic equation in one variable

An equation that can be written in the standard form ax2 + bx +c =0, where a, b, and c are real numbers and a is not zero.

Root of an equation

A solution of an equation.

Zero of a function

An x-value of a function f for which f(x) = 0.

Quadratic Formula

x = -b ± √(b² - 4ac)/2a