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If i=sqrt(-1), what is the product of (4...

If `i=sqrt(-1)`, what is the product of `(4+7i) and ((1)/(2)-2i)`?

A

`16-(9)/(2)i`

B

`14+(9)/(2)i`

C

`2-8i-14i^(2)`

D

`i(8+(9)/(2))`

Text Solution

AI Generated Solution

The correct Answer is:
To find the product of \( (4 + 7i) \) and \( \left( \frac{1}{2} - 2i \right) \), we can use the distributive property (also known as the FOIL method for binomials). Let's break it down step by step. ### Step 1: Write down the expression We need to calculate: \[ (4 + 7i) \left( \frac{1}{2} - 2i \right) \] ### Step 2: Distribute the terms Now, we will distribute each term in the first expression to each term in the second expression: \[ = 4 \cdot \frac{1}{2} + 4 \cdot (-2i) + 7i \cdot \frac{1}{2} + 7i \cdot (-2i) \] ### Step 3: Calculate each multiplication Now we calculate each of these products: 1. \( 4 \cdot \frac{1}{2} = 2 \) 2. \( 4 \cdot (-2i) = -8i \) 3. \( 7i \cdot \frac{1}{2} = \frac{7i}{2} \) 4. \( 7i \cdot (-2i) = -14i^2 \) ### Step 4: Substitute \( i^2 \) with \(-1\) Recall that \( i^2 = -1 \). Therefore, we can substitute: \[ -14i^2 = -14(-1) = 14 \] ### Step 5: Combine all the results Now we combine all the results: \[ = 2 - 8i + \frac{7i}{2} + 14 \] ### Step 6: Combine like terms Now, we combine the real parts and the imaginary parts: - Real parts: \( 2 + 14 = 16 \) - Imaginary parts: \( -8i + \frac{7i}{2} \) To combine the imaginary parts, we need a common denominator: \[ -8i = -\frac{16i}{2} \] Thus, \[ -\frac{16i}{2} + \frac{7i}{2} = -\frac{16i - 7i}{2} = -\frac{9i}{2} \] ### Final Result Putting it all together, we have: \[ 16 - \frac{9i}{2} \] Thus, the product of \( (4 + 7i) \) and \( \left( \frac{1}{2} - 2i \right) \) is: \[ \boxed{16 - \frac{9i}{2}} \]
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