Back to The Complex Number System — Problem 1 · Task Set 28

HSN.CN Tutor Intake — Complex Numbers

This short check helps your tutor understand where to start with complex numbers. Answer each question on your own without notes or a calculator. If you are unsure, give your best try — the goal is to find what to work on together, not to grade you.

Grade 10·12 problems·~14 min·Common Core Math - HS Number and Quantity·domain·cn

Work through problems with immediate feedback

Concepts

The imaginary unit $i$ is defined so that $i^2 = -1$ . Which
statement correctly explains why $i$ is defined this way?

Because $\sqrt{-1}$ can be computed by taking the negative
of $\sqrt{1} = 1$ .

Because no real number squares to $-1$ , so a new number
is defined to make $x^2 = -1$ solvable.

Because $i$ is an unknown variable, just like $x$ ,
that satisfies certain equations.

Because $i^2 = 1$ by the rules of squaring, and the
sign is changed by convention.