Evaluate this complex number multiplication
(2 + 3i)(9 - 8i)
Define the FOIL Formula:
(a * c) + (b * c) + (a * d) + (b * d)
Set the FOIL values:
a = 2, b = 3, c = 9, and d = -8
Plug in values:
(2 + 3i)(9 - 8i) = (2 * 9) + (3i * 9) + (2 * -8i) + (3i * -8i)
(2 + 3i)(9 - 8i) = 18 + 27i - 16i - 24i2
Group the like terms:
(2 + 3i)(9 - 8i) = 18 + (27 - 16)i - 24i2
(2 + 3i)(9 - 8i) = 18 + 11i - 24i2
Simplify our last term:
i2 = √-1 * √-1 = -1, so our last term becomes:
(2 + 3i)(9 - 8i) = 18 + 11i - 24* (-1)
(2 + 3i)(9 - 8i) = 18 + 11i + 24
Group the 2 constants
(2 + 3i)(9 - 8i) = (18 + 24) + 11i
Final Answer
42 + 11i
Common Core State Standards In This Lesson
HSN.CN.A.2, HSN.CN.A.3
What is the Answer?
42 + 11i
How does the Complex Number Operations Calculator work?
Free Complex Number Operations Calculator - Given two numbers in complex number notation, this calculator:
1) Adds (complex number addition), Subtracts (complex number subtraction), Multiplies (complex number multiplication), or Divides (complex number division) any 2 complex numbers in the form a + bi and c + di where i = √-1.
2) Determines the Square Root of a complex number denoted as √a + bi
3) Absolute Value of a Complex Number |a + bi|
4) Conjugate of a complex number a + bi
This calculator has 4 inputs.
1) Adds (complex number addition), Subtracts (complex number subtraction), Multiplies (complex number multiplication), or Divides (complex number division) any 2 complex numbers in the form a + bi and c + di where i = √-1.
2) Determines the Square Root of a complex number denoted as √a + bi
3) Absolute Value of a Complex Number |a + bi|
4) Conjugate of a complex number a + bi
This calculator has 4 inputs.
What 6 formulas are used for the Complex Number Operations Calculator?
a + bi + (c + di) = (a + c) + (b + d)i
a + bi - (c + di) = (a - c) + (b - d)i
(a * c) + (b * c) + (a * d) + (b * d)
The square root of a complex number a + bi, is denoted as root1 = x + yi and root2 = -x - yi
|a + bi| = sqrt(a2 + b2)
a + bi has a conjugate of a - bi and a - bi has a conjugate of a + bi.
a + bi - (c + di) = (a - c) + (b - d)i
(a * c) + (b * c) + (a * d) + (b * d)
The square root of a complex number a + bi, is denoted as root1 = x + yi and root2 = -x - yi
|a + bi| = sqrt(a2 + b2)
a + bi has a conjugate of a - bi and a - bi has a conjugate of a + bi.
What 8 concepts are covered in the Complex Number Operations Calculator?
- absolute value
- A positive number representing the distance from 0 on a number line
- addition
- math operation involving the sum of elements
- complex number
- a number that can be written in the form a + b or a - bi
- complex number operations
- conjugate
- A term formed by changing the sign between two terms in a binomial.
- division
- separate a number into parts
- multiplication
- math operation involving the product of elements
- subtraction
- math operation involving the difference of elements
