2.5 Complex Numbers

Algebra 2

Unit 2, Lesson 5

Complex
Numbers

Volume 1, pg. 98

Bellwork

volume 1, pg. 98

 Write down the following definition:

Learning Goals

volume 1, pg. 98

The students will be able to:

• define a complex number.

• add and subtract complex numbers.

volume 1, pg. 99

​

volume 1, pg. 99

The process of adding and subtracting complex numbers is similar to adding and subtracting polynomials. With polynomials, like terms are added or subtracted. With complex numbers, like parts are added or subtracted.

With your partner, perform the given operation for the complex numbers.

b.

3 − 5i − 7 − 2i

c.

7 + 5i + 4 − 8i

d.

5 + 2 i + 5 − 2i

​

volume 1, pg. 99

The process of adding and subtracting complex numbers is similar to adding and subtracting polynomials. With polynomials, like terms are added or subtracted. With complex numbers, like parts are added or subtracted.

With your partner, perform the given operation for the complex numbers.

b.

3 − 5i − 7 − 2i

c.

7 + 5i + 4 − 8i

d.

5 + 2 i + 5 − 2i

​

volume 1, pg. 99

The process of adding and subtracting complex numbers is similar to adding and subtracting polynomials. With polynomials, like terms are added or subtracted. With complex numbers, like parts are added or subtracted.

With your partner, perform the given operation for the complex numbers.

b.

3 − 5i − 7 − 2i

c.

7 + 5i + 4 − 8i

d.

5 + 2 i + 5 − 2i

​

volume 1, pg. 99

The process of adding and subtracting complex numbers is similar to adding and subtracting polynomials. With polynomials, like terms are added or subtracted. With complex numbers, like parts are added or subtracted.

With your partner, perform the given operation for the complex numbers.

b.

3 − 5i − 7 − 2i

c.

7 + 5i + 4 − 8i

d.

5 + 2 i + 5 − 2i

​

volume 1, pg. 99

The process of adding and subtracting complex numbers is similar to adding and subtracting polynomials. With polynomials, like terms are added or subtracted. With complex numbers, like parts are added or subtracted.

With your partner, perform the given operation for the complex numbers.

b.

3 − 5i − 7 − 2i

c.

7 + 5i + 4 − 8i

d.

5 + 2 i + 5 − 2i

​

volume 1, pg. 99

​

Multiple Choice

Add or subtract each complex expression.

$$\left(5+3i\right)\ +\ \left(6-8i\right)$$

• $$11-5i$$

• $$11+5i$$

• $$30-24i^2$$

• $$11+11i$$

Multiple Choice

Add or subtract each complex expression.

$$\left(3-2i\right)\ -\ \left(2-4i\right)$$

• $$1+2i$$

• $$1-6i$$

• $$5-6i^{ }$$

• $$5+6i$$

Multiple Choice

Add or subtract each complex expression.

$$6+\left(4-3i\right)$$

• $$10-3i$$

• $$24-18i$$

• $$10+3i^{ }$$

• $$2+9i$$

Multiple Choice

Add or subtract each complex expression.

$$\left(5+7i\right)-\left(5-7i\right)$$

• $$14i$$

• $$25-14i$$

• $$10$$

• $$0$$

Multiple Choice

Add or subtract each complex expression.

$$\left(5+7i\right)+\left(5-7i\right)$$

• $$14i$$

• $$25-14i$$

• $$10$$

• $$0$$