Lesson Example Discussion Quiz: Class Homework |
Step-1 |
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
Step | Type | Explanation | Answer |
---|---|---|---|
1 |
Problem |
Compute the product of the complex numbers (2 + 3i) and (4 − i). What is the result in standard form? |
|
2 |
Step |
Write down the expression: |
\$(2 + 3i) \times (4 - i)\$ |
3 |
Hint |
Apply the distributive property (FOIL method) to expand the product: |
\$(2 \times 4) + (2 \times (−i)) + (3i \times 4) + (3i \times (−i))\$ |
4 |
Step |
Perform each multiplication: |
\$2 \times 4 = 8\$ |
5 |
Step |
Multiply the real part of the first number by the imaginary part of the second number: |
\$2 \times (-i) = -2i\$ |
6 |
Step |
Multiply the imaginary part of the first number by the real part of the second number: |
\$3i \times 4 = 12i\$ |
7 |
Step |
Multiply the imaginary parts: |
\$3i \times (-i) = -3i^2\$ Recall that \$i^2 = -1\$, so: \$-3i^2 = -3(-1) = 3\$ |
8 |
Step |
Combine all the results: |
\$8 - 2i + 12i + 3\$ |
9 |
Step |
Combine the real and imaginary parts: |
11 + 10i |
10 |
Step |
TThe result of the product of (2+3i) and (4−i) in standard form is 11+10i. |
|
11 |
Choice.A |
This option represents a complex number with a positive real part and a negative imaginary part that does not match the result of our computation |
10 - 11i |
12 |
Choice.B |
This option represents a complex number with a negative real part and a negative imaginary part, which is not consistent with our computed result |
-11 - 10i |
13 |
Choice.C |
This option shows a complex number with a negative real part and a positive imaginary part, which does not correspond to our answer |
-10 + 5i |
14 |
Choice.D |
This option matches our computed result, which correctly combines the real part 11 and the imaginary part 10i |
11 + 10i |
15 |
Answer |
Option |
D |
16 |
Sumup |
Can you summarize what you’ve understood in the above steps? |
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