Question
Divide. Express your answer in standard form. \( \frac{-4}{2+3 i} \)
Ask by Montgomery Bowers. in the United States
Jan 27,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
\(-\dfrac{8}{13} + \dfrac{12}{13}\,i\)
Solution
To divide \(\frac{-4}{2 + 3i}\) and express the result in standard form \(a + bi\), follow these steps:
1. **Multiply by the Conjugate:**
Multiply both the numerator and the denominator by the conjugate of the denominator to eliminate the imaginary part in the denominator.
\[
\frac{-4}{2 + 3i} \times \frac{2 - 3i}{2 - 3i} = \frac{-4(2 - 3i)}{(2 + 3i)(2 - 3i)}
\]
2. **Simplify the Denominator:**
Use the difference of squares formula:
\[
(2 + 3i)(2 - 3i) = 2^2 - (3i)^2 = 4 - 9i^2 = 4 - 9(-1) = 4 + 9 = 13
\]
3. **Expand the Numerator:**
Distribute \(-4\) across \(2 - 3i\):
\[
-4(2 - 3i) = -8 + 12i
\]
4. **Combine the Results:**
\[
\frac{-8 + 12i}{13} = \frac{-8}{13} + \frac{12}{13}i
\]
Thus, the expression in standard form is:
\[
\boxed{ -\dfrac{8}{13} + \dfrac{12}{13}\,i }
\]
Reviewed and approved by the UpStudy tutoring team
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The Deep Dive
To simplify \( \frac{-4}{2+3i} \), multiply the numerator and denominator by the conjugate of the denominator, which is \( 2-3i \): \[ \frac{-4(2-3i)}{(2+3i)(2-3i)} = \frac{-8 + 12i}{4 + 9} = \frac{-8 + 12i}{13} \] Now, express it in standard form: \[ \frac{-8}{13} + \frac{12}{13}i \] So, the final answer in standard form is: \[ -\frac{8}{13} + \frac{12}{13}i \]