JEE Main 2022 · 29 June · Morning Shift · Mathematics · Complex Number
Let S = \ z ∈ C: |z - 2| ≤ 1, z(1 + i) + ¯ z (1 - i) ≤ 2\ . Let |z...
Let S={z∈C:∣z−2∣≤1,z(1+i)+z¯(1−i)≤2}. Let \left|z - 4i\right|attainsminimumandmaximumvalues,respectively,at{z}_{1} \in S and z2∈S. If 5(∣z1∣2+∣z2∣2)=α+β5, where α and β are integers, then the value of α+β is equal to ______.
Correct answer
0
Step-by-step solution
Given ∣z−2∣≤1
(x−2)2+y2≤1⋯(i) represents interior region of a circle with centre \left(2, 0\right) and radius 1
Now z(1+i)+z¯(1−i)≤2
Puting z=x+iy, we get
\left(x + iy\right)(1+i)+(x−iy)(1−i)≤2
⇒x−y+i(x+y)+x−y−i(x+y)≤2
∴x−y≤1…(i)
Let A(1,0) and B(2,1) be the points on the line x−y=1 and the circle (x−2)2+y2=1