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The imaginary number "I" is such that i^...

The imaginary number "I" is such that `i^(2)=-1`. Which of the following options is equivalent to `((1-2i)/(2+3i))` ?

A

`-(4)/(13)-i/13`

B

`(4)/(13)+i/13`

C

8-7i

D

`(8)/(13)+i`

Text Solution

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The correct Answer is:
To solve the expression \(\frac{1 - 2i}{2 + 3i}\), we will multiply both the numerator and the denominator by the conjugate of the denominator. The conjugate of \(2 + 3i\) is \(2 - 3i\). ### Step 1: Multiply by the conjugate \[ \frac{1 - 2i}{2 + 3i} \cdot \frac{2 - 3i}{2 - 3i} \] ### Step 2: Expand the numerator Using the distributive property (FOIL method): \[ (1 - 2i)(2 - 3i) = 1 \cdot 2 + 1 \cdot (-3i) - 2i \cdot 2 - 2i \cdot (-3i) \] Calculating each term: - \(1 \cdot 2 = 2\) - \(1 \cdot (-3i) = -3i\) - \(-2i \cdot 2 = -4i\) - \(-2i \cdot (-3i) = 6i^2\) (and since \(i^2 = -1\), this becomes \(6(-1) = -6\)) Now, combine these results: \[ 2 - 3i - 4i - 6 = 2 - 6 - 7i = -4 - 7i \] ### Step 3: Expand the denominator Using the formula \(a^2 - b^2\): \[ (2 + 3i)(2 - 3i) = 2^2 - (3i)^2 = 4 - 9i^2 \] Since \(i^2 = -1\), we have: \[ 4 - 9(-1) = 4 + 9 = 13 \] ### Step 4: Combine the results Now we can write the expression as: \[ \frac{-4 - 7i}{13} \] ### Step 5: Split the fraction This can be separated into real and imaginary parts: \[ -\frac{4}{13} - \frac{7}{13}i \] Thus, the final result is: \[ -\frac{4}{13} - \frac{7}{13}i \]
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