HSN-CN.A.1

Know there is a complex number i such that i^{2} = -1, and every complex number has the form a + bi with a and b real.

HSN-CN.A.2

Use the relation i^{2} = -1 and the commutative, associative, and distributive properties to add, subtract, and multiply complex numbers.

HSN-CN.A.3

(+) Find the conjugate of a complex number; use conjugates to find moduli and quotients of complex numbers.

HSN-CN.B.4

(+) Represent complex numbers on the complex plane in rectangular and polar form (including real and imaginary numbers), and explain why the rectangular and polar forms of a given complex number represent the same number.

HSN-CN.B.5

(+) Represent addition, subtraction, multiplication, and conjugation of complex numbers geometrically on the complex plane; use properties of this representation for computation. For example, (-1 + â3 i)^{3} = 8 because (-1 + â3 i) has modulus 2 and argument 120Â°.

HSN-CN.B.6

(+) Calculate the distance between numbers in the complex plane as the modulus of the difference, and the midpoint of a segment as the average of the numbers at its endpoints.

HSN-CN.C.7

Solve quadratic equations with real coefficients that have complex solutions.

HSN-CN.C.8

(+) Extend polynomial identities to the complex numbers. For example, rewrite x^{2} + 4 as (x + 2i)(x â 2i).

HSN-CN.C.9

(+) Know the Fundamental Theorem of Algebra; show that it is true for quadratic polynomials.