JEE MainMathematicsComplex NumbersMCQ+4 / −1
If z is a complex number such that , then the minimum value of :
- Ais strictly greater that
- Bis strictly greater that but less than
- Cis equal to
- Dlie in the interval (1, 2)
View written solutionFree
Correct answer: D
-
We need the minimum value of given that
-
Interpret this geometrically in the Argand plane.
- The condition means the point lies on or outside the circle centered at with radius .
- The quantity is the distance of from the fixed point on the real axis.
So we want the minimum distance from the point to the region .
-
The point lies inside the circle , since Hence the nearest point in the region will be on the boundary circle , along the line joining the origin and .
-
Therefore, the minimum distance is
We can also verify by triangle inequality: Since , Equality occurs when is on the negative real axis with , i.e. at Then So the minimum value is exactly
- Check options:
- A: strictly greater than — false
- B: strictly greater than but less than — false, because minimum equals , not strictly greater
- C: equal to — false
- D: lies in interval — true, since
Thus the correct option is
More from Complex Numbers
- If z is a complex number of unit modulus and argument , then arg equals :2013 · MCQ
- If and is real, then the point represented by the complex number z lies :2012 · MCQ
- Let be real and z be a complex number. If has two distinct roots on the line Re z = 1, then it is necessary that :2011 · MCQ
- If is a cube root of unity, and . Then equals :2011 · MCQ
- The number of complex numbers z such that equals :2010 · MCQ
- If then the maximum value of is equal to :2009 · MCQ
- The conjugate of a complex number is then that complex number is :2008 · MCQ
- If , then the maximum value of is :2007 · MCQ