Step-4

Title: Multiplication of complex numbers

Grade: 8-b Lesson: S2-L6

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Discussion: Step1 Step2 Step3 Step4 Step5

Step Type Explanation Answer

1

Problem

Multiply the following complex numbers ( -16 + 2i) and ( 8 - 8i).

2

Step

The given expression

( -16 + 2i) and ( 8 - 8i)

3

Hint

Apply the distributive property (FOIL method):

\$- 16 times 8 - 16 times ( - 8i) + 2i times 8 + 2i times (-8i)\$

4

Step

Calculate each term:

\$- 128 + 128i + 16i - 16i^2\$

5

Hint

Since \$i^2 = - 1\$.

6

Step

Plug the \$i^2 = - 1\$ in the above expression and then simplify it:

\$ - 128 + 144i - 16 times (-1)\$

⇒ - 128 + 144i + 16

⇒ - 112 + 144i

7

Step

Therefore the multiply of complex numbers is - 112 + 144i.

8

Choice.A

This result does not match our calculation because the signs of the real parts are incorrect. In the correct solution, the real part is −112, not 112

112 + 144i

9

Choice.B

Wrong: Because the real part of the product is - 112 (not 121), and the imaginary part is 144i (not - 144i)

121 - 144i

10

Choice.C

The calculation of complex numbers confirms the accuracy of this option, making it the correct choice

-112 + 144i i

11

Choice.D

The real part should be −112, not −121. So, this is option is wrong

-121 + 144i

12

Answer

Option

C

13

Sumup

Can you summarize what you’ve understood in the above steps?

Discussion: Step1 Step2 Step3 Step4 Step5


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