Precalculus Complex Numbers and Complex Zeros Quiz: 10 Questions with Explanations

Precalculus math quiz: Complex Numbers and Complex Zeros – Maths PDF

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This precalculus complex numbers quiz for Precalculus covers complex numbers and complex zeros (Common Core N-CN.A.1, N-CN.A.2, N-CN.A.3, N-CN.C.7, N-CN.C.8, N-CN.C.9), with a free PDF to print.

Pick the best answer for 10 questions on complex numbers. Explanations show the usual mistakes, such as forgetting that i squared is -1.

Precalculus · Common Core State Standards: N-CN.A.1, N-CN.A.2, N-CN.A.3, N-CN.C.7, N-CN.C.8, N-CN.C.9

Precalculus complex numbers quiz: 10 questions

Question 1

What is \(i^{2}\)?

Question 2

Simplify \(i^{15}\).

Question 3

The figure shows the sum of two complex numbers. What is \((3+5i)+(-1+2i)\)?

Vector sum.

Question 4

Multiply: \((1+2i)(3-i)\).

Question 5

Which is the conjugate of \(4-7i\)?

Question 6

What is \(|3+4i|\)?

The point 3 + 4i.

Question 7

The graph of a parabola never meets the \(x\)-axis. What kind of roots does the equation have?

Parabola above the x-axis.

Question 8

Solve \(x^{2}+9=0\).

Question 9

A polynomial with real coefficients has the zero \(3+2i\). Which must also be a zero?

Question 10

How many complex zeros does a degree-6 polynomial have, counting multiplicity?

Remember

i^2 = -1, and powers of i repeat in a cycle of 4: i, -1, -i, 1.
The conjugate of a + bi is a – bi, and (a + bi)(a – bi) = a^2 + b^2.
Modulus: |a + bi| = sqrt(a^2 + b^2), the distance from the origin in the complex plane.
A negative discriminant gives two complex roots that are conjugates.
Fundamental Theorem of Algebra: a degree-n polynomial has n complex zeros counting multiplicity.

How to use this precalculus complex numbers quiz

Answer each question, read the explanation that appears, and keep track of your score. A score of 8 out of 10 or more means you are ready for the test.

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