adding subtracting multiplying and dividing complex numbers

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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, defined as the square root of -1.

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CCSS.HSN.CN.A.1

Front

How do you add two complex numbers?

Back

To add two complex numbers, combine their real parts and their 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 subtract two complex numbers?

Back

To subtract two complex numbers, subtract their real parts and their imaginary parts separately. For example, (a + bi) - (c + di) = (a - c) + (b - d)i.

Tags

CCSS.HSN.CN.A.2

Front

What is the product of two complex numbers (a + bi)(c + di)?

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The product is given by (ac - bd) + (ad + bc)i, using the distributive property and the fact that i^2 = -1.

Tags

CCSS.HSN.CN.A.2

Front

What is the conjugate of a complex number a + bi?

Back

The conjugate of a complex number a + bi is a - bi. It is obtained by changing the sign of the imaginary part.

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CCSS.HSN.CN.A.3

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How do you multiply a complex number by its conjugate?

Back

Multiplying a complex number by its conjugate results in a real number: (a + bi)(a - bi) = a^2 + b^2.

Tags

CCSS.HSN.CN.A.2

Front

What is the modulus of a complex number a + bi?

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The modulus (or absolute value) of a complex number a + bi is given by √(a^2 + b^2).

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How do you divide two complex numbers?

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To divide two complex numbers, multiply the numerator and denominator by the conjugate of the denominator. For example, (a + bi) / (c + di) = [(a + bi)(c - di)] / (c^2 + d^2).

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CCSS.HSN.CN.A.3

Front

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

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The result is -12 - 6i.

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CCSS.HSN.CN.A.2

Front

What is the result of (-7 + 9i) + (2 - 10i)?

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The result is -5 - i.

Tags

CCSS.HSN.CN.A.2