Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202229 JuneMorning Shift
Exam
JEE Main
Year
2022
Date
29 June
Shift
Morning Shift
Subject
Mathematics
Chapter
Complex Number

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}S = \left\{z \in C: \left|z - 2\right| \le 1, z\left(1 + i\right) + \overset{¯}{z}\left(1 - i\right) \le 2\right\}. Let \left|z - 4i\right|attainsminimumandmaximumvalues,respectively,atattains minimum and maximum values, respectively, at{z}_{1} \in S and z2∈S{z}_{2} \in S. If 5(∣z1∣2+∣z2∣2)=α+β55\left({\left|{z}_{1}\right|}^{2} + {\left|{z}_{2}\right|}^{2}\right) = \alpha + \beta\sqrt{5}, where α\alpha and β\beta are integers, then the value of α+β\alpha + \beta is equal to ______.Let S = \ z ∈ C: |z - 2| ≤ 1, z(1 + i) + ¯ z (1 - i) ≤ 2\ . Let |z - 4i| attains minimum and maximum values,

Correct answer

0

Step-by-step solution

Given ∣z−2∣≤1\left|z - 2\right| \le 1

(x−2)2+y2≤1⋯(i){\left(x - 2\right)}^{2} + {y}^{2} \le 1 ⋯ \left(i\right) represents interior region of a circle with centre \left(2, 0\right) and radius 11

Now z(1+i)+z¯(1−i)≤2z\left(1 + i\right) + \overset{¯}{z}\left(1 - i\right) \le 2

Puting z=x+iyz = x + iy, we get

\left(x + iy\right)(1+i)+(x−iy)(1−i)≤2\left(1 + i\right) + \left(x - iy\right)\left(1 - i\right) \le 2

⇒x−y+i(x+y)+x−y−i(x+y)≤2⇒ x - y + i\left(x + y\right) + x - y - i\left(x + y\right) \le 2

∴x−y≤1…(i)∴ x - y \le 1 \ldots \left(i\right)

Let A(1,0)A\left(1, 0\right) and B(2,1)B\left(2, 1\right) be the points on the line x−y=1x - y = 1 and the circle (x−2)2+y2=1{\left(x - 2\right)}^{2} + {y}^{2} = 1

\left|z - 4i\right|representsthedistancefromrepresents the distance fromP\left(0, 4\right)toanypointintheregionto any point in the regionS</p><p><imgsrc="https://cdn−question−pool.getmarks.app/pyq/jeemain/a90ce137−3cc0−4687−8ab8−8e17a3497c06−image.png"style="width:257px;height:200px;"/></p><p>Here</p><p><img src="https://cdn-question-pool.Quantrex.app/pyq/jee_main/a90ce137-3cc0-4687-8ab8-8e17a3497c06-image.png" style="width: 257px; height: 200px;" /></p><p>HerePA = \sqrt{17}, PB = \sqrt{13}</p><p>So</p><p>SoA\left(1, 0\right)isthepointrepresentingis the point representing{z}_{2}</p><p>Let</p><p>LetD\left(2 + cos\theta, 0 + sin\theta\right)bethepointrepresentingbe the point representing{z}_{1}</p><p></p><p>∴ {m}_{CP} = tan\theta = - 2</p><p></p><p>cos\theta = - \dfrac{1}{\sqrt{5}}, sin\theta = \dfrac{2}{\sqrt{5}}</p><p></p><p>∴ D ≡ \left(2 - \dfrac{1}{\sqrt{5}}, \dfrac{2}{\sqrt{5}}\right)</p><p></p><p>⇒ {z}_{1} = \left(2 - \dfrac{1}{\sqrt{5}}\right) + \dfrac{2i}{\sqrt{5}}</p><p>So∣z1∣=25−455 and z2=1</p><p>So \left|{z}_{1}\right| = \dfrac{25 - 4\sqrt{5}}{5} \text{ and } {z}_{2} = 1

∴∣z2∣2=1∴ {\left|{z}_{2}\right|}^{2} = 1

∴5(∣z1∣2+∣z2∣2)=30−45∴ 5\left({\left|{z}_{1}\right|}^{2} + {\left|{z}_{2}\right|}^{2}\right) = 30 - 4\sqrt{5}

∴α=30∴ \alpha = 30

β=−4\beta = - 4

Hence α+β=26\alpha + \beta = 26

Practice Complex Number on Quantrex Academy →

More from Complex Number

The number of values of z ∈ ℂ , satisfying the equations |z-(4+8i)|= 10 and… JEE Main 2026Let S = \ z ∈ ℂ : z^2 + 6 \,iz - 3 = 0\ . Then ∑ _ z ∈ S z^8 is equal to : JEE Main 2026Let the set of all values of k ∈ ℝ such that the equation z( z + 2 + i) + k(2 + 3i) = 0… JEE Main 2026Let z_1, z_2 ∈ ℂ be the distinct solutions of the equation z^2 + 4z - (1 + 12i) = 0 .… JEE Main 2026Let S=\ z ∈ ℂ: z^2+4z+16=0\ . Then ∑_ z ∈ S |z+ 3 i|^2 is equal to: JEE Main 2026Let z be a complex number such that |z+2| = |z-2| and ((z+3)/(z-i)) = (π)/(4) . Then… JEE Main 2026Let the circles C_1 : |z| = r and C_2 : |z - 3 - 4i| = 5 , z ∈ ℂ , be such that C_2 lies… JEE Main 2026Let x and y be real numbers such that 50((2x)/(1+3i) - (y)/(1-2i)) = 31 + 17i , i = -1 .… JEE Main 2026Let A=\ z ∈ ℂ:|z-2| 4\ and B=\ z ∈ ℂ:|z-2|+|z+2|=5\ . Then the max \ |z_ 1 -z_ 2 |: z_ 1… JEE Main 2026Let z be a complex number such that |z-6|=5 and |z+2-6 i|=5 . Then the value of z^ 3 +3… JEE Main 2026Let z=(1+i)(1+2 i)(1+3 i) …(1+n i) , where i= -1 . If |z|^ 2 =44200 , then n is equal to… JEE Main 2026If z= 3 2 +(i)/(2), i= -1 , then (z^ 201 -i)^ 8 is equal to JEE Main 2026Let S=\ z: 3 |2 z-3(1+i)| 7\ be a set of complex numbers. Then _ z ∈ S |(z+(1)/(2)(5+3… JEE Main 2026Let S=\ z ∈ ℂ: 4 z^ 2 + z =0\ . Then ∑_ z ∈ S |z|^ 2 is equal to: JEE Main 2026Let α= -1+i 3 2 and β= -1-i 3 2 , i= -1 . If (7-7 α+9 β)^ 20 +(9+7 α-7 β)^ 20 +(-7+9 α+7… JEE Main 2026Let z be the complex number satisfying |z-5| ≤ 3 and having maximum positive principal… JEE Main 2026 Full Complex Number list Complex Number JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs