NTA Abhyas JEE Main2020MathematicsComplex NumberPractice
If z be a complex number satisfying | z – 4 + 8 i | = 4 , then the least and the greatest value of | z + 2 | are respectively (where i = - 1 )
Options
- A7 and 16
- B8 and 17
- C6 and 14
- D5 and 13
Correct answer
C. 6 and 14
Step-by-step solution
| z + 2 | = | z + 2 – 4 + 8 i + 4 – 8 i | | z + 2 | = | z – 4 + 8 i + 6 – 8 i | z + 2 ≤ | z - 4 + 8 i | + | 6 - 8 i | ≤ 4 + 10 = 14 | z + 2 | = | z + 2 – 4 + 8 i + 4 – 8 i | ≥ | z - 4 + 8 i | - | 6 - 8 i | ≥ 4 - 10 = 6