Grade 11 · Math · Algebra 2

11th grade Complex conjugates, and dividing complex numbers worksheet

6 printable versionsOn Level10 questions · answer keyFree · no account

When it’s done, scan the sheet with your phone and PencilGo marks it and picks the next one. Create a free account

Version

Complex conjugates, and dividing complex numbers

Grade 11 Math Worksheet

NameDate

Circle the best answer, or write your answer on the line.

Tala divides on a math club card. Write the answer in a + bi form. What is (5 + 5i) ÷ (1 + 2i)?
Zee divides 3 − i by 1 − i on the board. Write the answer in a + bi form. What is (3 − i) ÷ (1 − i)?
Jun divides two grid map pins. Write the answer in a + bi form. What is (8 + i) ÷ (2 − i)?
Kira divides a puzzle number by 2i. Write the answer in a + bi form. What is (6 + 4i) ÷ (2i)?
Luz works out (8 − 12i) ÷ (4i) on the board. What is (8 − 12i) ÷ (4i) in a + bi form?
Milo's robot divides its spot by 5i, a quarter turn back and a shrink. What is (-5 + 10i) ÷ (5i)?
Noah divides a grid map pin by -3i. Write the answer in a + bi form. What is (9 + 3i) ÷ (-3i)?
8.
Pia wants to divide (7 − i) by (2 − 3i). What should the top and bottom both be multiplied by?
- 7 + i
- 2 − 3i
- 2 + 3i
- -2 − 3i
9.
Ren divides (4 + 5i) by (-1 + 2i) on the board. What should the top and bottom both be multiplied by?
- 1 + 2i
- -1 − 2i
- -1 + 2i
- 4 − 5i
10.
Tala uses a mirror idea to divide (-3 + 2i) by (5 + 4i). What should the top and bottom both be multiplied by?
- -3 − 2i
- -5 + 4i
- 5 − 4i
- 5 + 4i

Complex conjugates, and dividing complex numbers. Every version has 10 questions, and the answer key prints on the second page.

I can write a conjugate by flipping a point across the real axis.
I can multiply a number by its conjugate and get a real number.
I can divide complex numbers by multiplying the top and bottom by the conjugate of the bottom.

Standard: N-CN.A.3 (+)

conjugate: The mirror image across the real axis: a + bi becomes a − bi.

real axis: The across line through 0.

reciprocal: The number that multiplies to make 1.

denominator: The bottom of a fraction.

Your child changed the sign of the real part to make the conjugate.

Your child changed both signs, which is the opposite number, not the conjugate.

Your child used i² = 1 instead of i² = -1.

Ask: when a point is flipped across the across line, which part changes?

Ask: does a flip across the across line move a point left or right?

Ask: what is i × i?

What is the most common mistake with complex conjugates, and dividing complex numbers?

Your child changed the sign of the real part to make the conjugate.

How can I help my child with complex conjugates, and dividing complex numbers?

Ask: when a point is flipped across the across line, which part changes?

Are these 11th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

Every sheet you scan goes into your child’s record: dated, marked and ready for the year-end portfolio. Homeschool records