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The number of points in the complex plan...

The number of points in the complex plane that satisfy the conditions `| z- 2| = 2 sqrt(2) , z ( 1- i) + bar(z) (1 + i) = 4 ` is

A

0

B

1

C

2

D

more than 2

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The correct Answer is:
To solve the problem, we need to find the number of points in the complex plane that satisfy the given conditions: 1. \( |z - 2| = 2\sqrt{2} \) 2. \( z(1 - i) + \overline{z}(1 + i) = 4 \) Let's denote the complex number \( z \) as \( z = x + iy \), where \( x \) and \( y \) are real numbers. ### Step 1: Analyze the first condition The first condition \( |z - 2| = 2\sqrt{2} \) can be interpreted as the equation of a circle in the complex plane centered at \( (2, 0) \) with a radius of \( 2\sqrt{2} \). ### Step 2: Analyze the second condition The second condition involves \( z(1 - i) + \overline{z}(1 + i) = 4 \). We can rewrite this using \( z = x + iy \) and \( \overline{z} = x - iy \): \[ (x + iy)(1 - i) + (x - iy)(1 + i) = 4 \] ### Step 3: Expand the second condition Expanding the left-hand side: \[ (x + iy)(1 - i) = x(1) + x(-i) + iy(1) + iy(-i) = x - ix + iy + y = (x + y) + i(y - x) \] \[ (x - iy)(1 + i) = x(1) + x(i) - iy(1) - iy(i) = x + ix - iy - y = (x - y) + i(x - y) \] Now combine both parts: \[ ((x + y) + i(y - x)) + ((x - y) + i(x + y)) = 4 \] ### Step 4: Combine real and imaginary parts Combining the real parts and the imaginary parts gives: Real part: \( (x + y) + (x - y) = 2x \) Imaginary part: \( (y - x) + (x + y) = 2y \) Thus, we have: \[ 2x + 2y = 4 \] Dividing through by 2: \[ x + y = 2 \quad \text{(Equation 1)} \] ### Step 5: Substitute \( y \) in terms of \( x \) From Equation 1, we can express \( y \) in terms of \( x \): \[ y = 2 - x \] ### Step 6: Substitute into the first condition Now substitute \( y = 2 - x \) into the first condition \( |z - 2| = 2\sqrt{2} \): \[ |x + i(2 - x) - 2| = 2\sqrt{2} \] This simplifies to: \[ |x - 2 + i(2 - x)| = 2\sqrt{2} \] Taking the modulus: \[ \sqrt{(x - 2)^2 + (2 - x)^2} = 2\sqrt{2} \] ### Step 7: Simplify the modulus equation Squaring both sides: \[ (x - 2)^2 + (2 - x)^2 = 8 \] Expanding both terms: \[ (x - 2)^2 = x^2 - 4x + 4 \] \[ (2 - x)^2 = 4 - 4x + x^2 \] Adding these gives: \[ x^2 - 4x + 4 + 4 - 4x + x^2 = 8 \] This simplifies to: \[ 2x^2 - 8x + 8 = 8 \] ### Step 8: Solve the quadratic equation Subtracting 8 from both sides: \[ 2x^2 - 8x = 0 \] Factoring out \( 2x \): \[ 2x(x - 4) = 0 \] This gives us: \[ x = 0 \quad \text{or} \quad x = 4 \] ### Step 9: Find corresponding \( y \) values For \( x = 0 \): \[ y = 2 - 0 = 2 \quad \Rightarrow \quad (0, 2) \] For \( x = 4 \): \[ y = 2 - 4 = -2 \quad \Rightarrow \quad (4, -2) \] ### Conclusion Thus, the points that satisfy both conditions are \( (0, 2) \) and \( (4, -2) \). Therefore, the number of points in the complex plane that satisfy the conditions is: **Answer: 2 points**
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ML KHANNA-COMPLEX NUMBERS -Problem Set (3) (M.C.Q)
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  2. If (x+i y)(p+i q)=(x^2+y^2)i , prove that x=q ,=pdot

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  3. The real part of ( 1- cos theta + 2 i sin theta )^(-1) is

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  4. The number of solutions of the equation z^2=barz is

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  5. The number of solutions of z^(2) + 2 bar(z) = 0 is

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  6. Number of solutions of the equation z^(2)+|z|^(2)=0, where z in C, is

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  7. The solution of the equation |z|-z=1+2i is

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  8. Find a complex number z satisfying the equation z+sqrt(2)|z+1|+i=0.

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  9. The number of solutions of the system of equations "Re(z^(2))=0, |z|=2...

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  10. The system of equations |z+1-i|=sqrt2 and |z| = 3 has

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  11. The number of jsolutions of the equation z^(2)+barz=0, is

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  12. The number of solutions of the equation z^(3)+barz=0, is

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  13. The number of points in the complex plane that satisfy the conditions ...

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  14. The number of values of z which satisfy both the equations |z-1-i|=sqr...

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  15. The solution of the equation |z|-z=1+2i is

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  16. If z^(2)+(p+iq)z+(r+is)=0, where,p,q,r,s are non-zero has real roots,...

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  17. If f(x) =x^4-8x^3+4x^2+4x+39 and f (3 + 2i) = a + ib then a : b is eq...

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  18. The equation barbz+bbarz=c, where b is a non-zero complex constant and...

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  19. Let a and b be two non- zero complex numbers. If the lines a bar(z) ...

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  20. The closest distance of origin from the curve given by b bar(z) + bar...

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