2.4 Alg 2 Operations on Complex Numbers

2.4 Alg 2 Operations on Complex Numbers

You have until 1:45 to answer 4 warm up questions. At 1:45 you will meet in breakout rooms for 5 mins to discuss your answers after which we will discuss together as a class.

Okay, let's get started.

Give these two problem a try...It's related to our topic for today!

Open Ended

 $Solve\ for\ x\ :\ \ x^2-4=5$  

Open Ended

 $Solve\ for\ x:\ \ \ \ x^2+4=-5$  

Multiple Choice

Simplify

• ± 4i √2
• ± 4 √2
• ± 2i √8
• ± 2 √8

Multiple Choice

Simplify

• 5i
• -5i
• ±5i
• ±

Multiple Choice

Simplify -√-8

• -i√8
• -2i√2
• 2i√2
• -8i

Complex Numbers are any combination of Real and/or Imaginary Numbers...

• 7 can be written in complex form: 7+ 0i

• 4i can be written in complex form: 0 + 4i

Multiple Choice

Which of the is a complex number?

• 2

• 4i

• 3 + 5i

• All of them

• none of them

It is important for you to write answers in correct complex form after simplifying an expression or solving an equation involving imaginary numbers...

Multiple Choice

How do you write a complex number?

• a-bi

• a+bi

• ai+b

• ai-b

Multiple Choice

2 - √-9

• 2-3i

• 2+3= 5

• 2+3i

• 2 - 3= -1

Division is a bit special, we will look at those a little later...

Multiple Choice

What is the simplified form of (-9 + 5i) + (3 -2i)

• -12 + 31i

• -6 + 3i

• -11 + 7i

• 5 - 3i

Multiple Choice

What is the simplifies form of (11 - 7i) - (-3 + 12i)

• 8 - 19i

• 8 + 5i

• 13- 19i

• 14 -19i

Now we will multiply, BUT remember this BIG IDEA we discussed earlier...

 $i^2=-1$  

This is very important and will come up A LOT in this course.

Multiple Choice

What does i² = ?

• -1
• √-1
• 1
• -√1

Multiple Choice

What is the simplified form of (-6i)(3i)

• -18

• -18i

• 18

• -18i²

Multiple Choice

What is the simplified form of (-3 + 2i)(1- 4i)

• -2 - 2i

• 5 + 14i

• -11 -10i

• -3 -8i

Multiple Choice

What is the simplified form of (8 -3i)²?

• 73

• 16 - 6i

• 55 + 48i

• 55 - 48i

Now it's time to practice!

Please complete the quizizz in breakout groups or hw if we are short on time!