AP EAMCET2002MathematicsComplex Number
If 3+2 i 1-2 i is a real number and 0 < < 2 , then is equal to
Options
- A6
- B3
- C2
Correct answer
A. 6
Step-by-step solution
We have aligned (3+2 i ) (1-2 i ) & = (3+2 i )(1+2 i ) (1-2 i )(1-2 i ) & = 3-4 ^2 +8 i 1+4 ^2 & = (3-4 ^2 ) (1+4 ^2 ) +i ( 8 1+4 ^2 ) aligned For a real number, gathered 8 1+4 ^2 =0 =0 = gathered