Machine-translated by Google. Questions are authored in English.
Top

Discussion

Imaginary parts of \(\left(\frac{3 - 2i}{2i}\right)^{2}\) is equal to

  • A.\(\frac{5}{4}\)
  • B.\(\frac{-5}{4}\)
  • C.3
  • D.-3
  • E.\(\frac{3}{4}\)

Answer: C

The imaginary part is 3.

Simplify the fraction first by multiplying top and bottom by \(-i\):

\[ \begin{aligned} \frac{3 - 2i}{2i} &= \frac{(3 - 2i)(-i)}{2} = \frac{-2 - 3i}{2} \\ \left(\frac{-2 - 3i}{2}\right)^{2} &= \frac{4 + 12i + 9i^{2}}{4} \\ &= \frac{-5 + 12i}{4} = -\frac{5}{4} + 3i \end{aligned} \]

So the imaginary part is 3. \(-\frac{5}{4}\) is the real part, which is the trap; \(\frac{5}{4}\), \(-3\) and \(\frac{3}{4}\) come from sign or scaling slips.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.