The document discusses imaginary numbers. Imaginary numbers are represented by the symbol i, where i = √-1. Standard form for imaginary numbers is a + bi. Rules for adding, subtracting, multiplying and dividing imaginary numbers are provided. When dividing, terms cannot have i in the denominator, and the expression must be multiplied by the same term with the opposite sign. The quadratic formula can produce imaginary number solutions when the expression under the square root is negative.