Imaginary and Complex Numbers

Front

What is an imaginary number?

Back

An imaginary number is a number that can be written as a real number multiplied by the imaginary unit 'i', where i is defined as the square root of -1.

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CCSS.HSN.CN.A.1

Front

What is a complex number?

Back

A complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is the imaginary unit.

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CCSS.HSN.CN.A.1

Front

What is the value of i^2?

Back

i^2 = -1.

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CCSS.HSN.CN.A.1

Front

How do you add complex numbers?

Back

To add complex numbers, combine the real parts and the imaginary parts separately. For example, (a + bi) + (c + di) = (a + c) + (b + d)i.

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CCSS.HSN.CN.A.2

Front

How do you multiply complex numbers?

Back

To multiply complex numbers, use the distributive property (FOIL method). For example, (a + bi)(c + di) = ac + adi + bci + bdi^2, and then simplify using i^2 = -1.

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CCSS.HSN.CN.A.2

Front

What is the conjugate of a complex number?

Back

The conjugate of a complex number a + bi is a - bi. It is used to simplify division of complex numbers.

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CCSS.HSN.CN.A.3

Front

What is the modulus of a complex number?

Back

The modulus of a complex number a + bi is given by |a + bi| = √(a² + b²). It represents the distance from the origin in the complex plane.

Front

How do you divide complex numbers?

Back

To divide complex numbers, multiply the numerator and denominator by the conjugate of the denominator. For example, to divide (a + bi) by (c + di), multiply by (c - di)/(c - di).

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CCSS.HSN.CN.A.3

Front

What is the result of (2 - 3i) + (4 + 5i)?

Back

(2 - 3i) + (4 + 5i) = (2 + 4) + (-3 + 5)i = 6 + 2i.

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CCSS.HSN.CN.A.2

Front

What is the result of (1 + 2i)(3 - 4i)?

Back

(1 + 2i)(3 - 4i) = 3 - 4i + 6i - 8i^2 = 3 + 2i + 8 = 11 + 2i.

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CCSS.HSN.CN.A.2