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Evaluate (2+3i)(4-5i)....

Evaluate `(2+3i)(4-5i).`

A

`-7-23i`

B

`-7+2i`

C

`23-7i`

D

`23+2i`

Text Solution

AI Generated Solution

The correct Answer is:
To evaluate the expression \((2 + 3i)(4 - 5i)\), we will use the distributive property (also known as the FOIL method for binomials). Here’s a step-by-step breakdown of the solution: ### Step 1: Identify the components We identify the components of the complex numbers: - \(a = 2\) - \(b = 3i\) - \(c = 4\) - \(d = -5i\) ### Step 2: Apply the distributive property Using the formula \((a + b)(c + d) = ac + ad + bc + bd\), we can substitute our values: \[ (2 + 3i)(4 - 5i) = 2 \cdot 4 + 2 \cdot (-5i) + 3i \cdot 4 + 3i \cdot (-5i) \] ### Step 3: Calculate each term Now we calculate each term: 1. \(2 \cdot 4 = 8\) 2. \(2 \cdot (-5i) = -10i\) 3. \(3i \cdot 4 = 12i\) 4. \(3i \cdot (-5i) = -15i^2\) ### Step 4: Substitute \(i^2\) Recall that \(i^2 = -1\). Thus, we can substitute: \[ -15i^2 = -15(-1) = 15 \] ### Step 5: Combine all terms Now we combine all the calculated terms: \[ 8 - 10i + 12i + 15 \] Combine the real parts and the imaginary parts: \[ (8 + 15) + (-10i + 12i) = 23 + 2i \] ### Final Answer Thus, the product of the complex numbers \((2 + 3i)(4 - 5i)\) is: \[ \boxed{23 + 2i} \]

To evaluate the expression \((2 + 3i)(4 - 5i)\), we will use the distributive property (also known as the FOIL method for binomials). Here’s a step-by-step breakdown of the solution: ### Step 1: Identify the components We identify the components of the complex numbers: - \(a = 2\) - \(b = 3i\) - \(c = 4\) - \(d = -5i\) ...
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