Complex Number Calculation: Real, Imaginary, and Absolute Value Explanation

Click For Summary
The discussion focuses on calculating the real part, imaginary part, and absolute value of the expression i * [(1+2i)(5-3i)+3i/(1+i)]. The initial calculations yield (1+2i)(5-3i) = 11+7i, leading to (11+7i)+3i/(1+i) = (4+21i)/(1+i). The user confirms that multiplying by the conjugate simplifies the expression, ultimately leading to (4i-21)/(1+i). The conversation clarifies that when a denominator contains an imaginary unit, the real and imaginary parts can still be identified through simplification. The thread concludes with the user successfully resolving their query.
JaysFan31
Calculate the real part, the imaginary part, and the absolute value of the following expression:

i * [(1+2i)(5-3i)+3i/(1+i)].


So I did the math out this way:

(1+2i)(5-3i)= 11+7i
(11+7i)+3i/(1+i)= (4+21i)/(1+i)
i * [(4+21i)/(1+i)] = (4i-21)/(1+i)

Is this correct and what do you call the imaginary part and the real part if a denominator exists with an imaginary i?

Thanks for any help.
 
Physics news on Phys.org
Yeah I figured it out. You just multiply it by its conjugate earlier in the process.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
Replies
9
Views
2K
  • · Replies 9 ·
Replies
9
Views
5K
  • · Replies 8 ·
Replies
8
Views
1K
Replies
1
Views
1K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 19 ·
Replies
19
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K