Grade 11 · Math · Algebra 2

11th grade Complex conjugates, and dividing complex numbers worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

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Complex conjugates, and dividing complex numbers

Grade 11 Math Worksheet - Building Confidence

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

Pia holds a mirror along the real axis to flip 4 − 7i. What is the conjugate of 4 − 7i?
Ren flips the pin at -3 + 5i across the real axis on a grid map. What is the conjugate of -3 + 5i?
Tala writes the conjugate of -8 − 2i on a puzzle card. What is the conjugate of -8 − 2i?
Esme multiplies 3 + 5i by its mirror image, 3 − 5i. What is (3 + 5i)(3 − 5i)?
Jun multiplies a number by its conjugate on a puzzle card. What is (7 − 2i)(7 + 2i)?
Kira works out (-1 + 6i)(-1 − 6i) on the board. What is (-1 + 6i)(-1 − 6i)?
Milo shares 12 − 8i into 4 equal steps from 0. What is (12 − 8i) ÷ 4?
Noah divides a puzzle number by 5. What is (-15 + 10i) ÷ 5?
Pia's robot shrinks its trip from 0 to 6 + 9i down to one third. What is (6 + 9i) ÷ 3?
Ren divides a grid map pin, 14 − 21i, by 7. What is (14 − 21i) ÷ 7?

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.

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