Math 10B: Conjugate and Division of complex Numbers(High Flyers)

Multiple Choice

What is the conjugate of -2+5i?

• -5+2i

• -2-5i

• 2+5i

• 5-2i

Multiple Choice

Simplify:  (4+2i)/(3-i)

• 1-i
• 1+i
• 10+10i
• 1+10i

Multiple Choice

Simplify

• (-10+6i)/17

• (1+50i)/61

• (-23+36i)/25

• (-21+33i)/34

Dividing Complex numbers

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Review of multiplying complex numbers

Remember i² = -1

Multiple Choice

(i)(3i)

• -3i
• -3
• 3
• 2i

Multiple Choice

(-3-i)(6-i)

• -21-7i
• -19-3i
• -15-5i
• -17-9i

Multiple Choice

(7-5i)(7+5i)

• 74
• 75
• 74-1

Find the conjugate

The conjugate of a + bi is a - bi

The conjugate of a - bi is a + bi

Multiple Choice

What is the conjugate of 2 + 3i?

• 2 - 3i

• -2 + 3i

• -2 - 3i

• 2 + 3i

Multiple Choice

What is the conjugate of -5 + 4i

• 5 + 4i

• 5 - 4i

• -5 - 4i

• -5 + 4i

Multiple Choice

What is the conjugate of 4i?

• 4i

• 4 + 4i

• 4-4i

• -4i

To divide complex numbers

Multiply the top and bottom by the conjugate of the denominator

Multiple Choice

 $\frac{5-8i}{3+2i}$  , what do you do to divide?

• Multiply the top and bottom by 3-2i

• Multiply the top and bottom by 5 + 8i

• multiply the top by 5 + 8i and the bottom by 3 - 2i

• Multiply the top and bottom by -3 - 2i

Multiple Choice

Simplify

Multiple Choice

• A
• B
• C
• D

Multiple Choice

• A
• B
• C
• D

Multiple Choice

• A
• B
• C
• D