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If at least one value of the complex num...

If at least one value of the complex number `z=x+iy` satisfies the condition `|z+sqrt(2)|=sqrt(a^(2)-3a+2)` and the inequality `|z+isqrt(2)| lt a`, then

A

`a gt 2`

B

`a=2`

C

`a lt 2`

D

`a gt 1`

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The correct Answer is:
To solve the problem, we need to analyze the given conditions involving the complex number \( z = x + iy \). ### Step 1: Understand the conditions We have two conditions: 1. \( |z + \sqrt{2}| = \sqrt{a^2 - 3a + 2} \) 2. \( |z + i\sqrt{2}| < a \) ### Step 2: Rewrite the first condition The first condition can be interpreted geometrically. The expression \( |z + \sqrt{2}| \) represents the distance from the point \( z \) to the point \( -\sqrt{2} \) in the complex plane. Thus, we can write: \[ |z + \sqrt{2}| = |(x + iy) + \sqrt{2}| = |(x + \sqrt{2}) + iy| \] This means the center of the circle is at \( (-\sqrt{2}, 0) \) and the radius is \( \sqrt{a^2 - 3a + 2} \). ### Step 3: Ensure the radius is positive For the radius to be valid, we need: \[ a^2 - 3a + 2 > 0 \] Factoring this quadratic inequality gives: \[ (a - 1)(a - 2) > 0 \] ### Step 4: Solve the inequality To find the intervals where this inequality holds, we find the roots: - \( a = 1 \) - \( a = 2 \) We can test intervals around these points: - For \( a < 1 \): Choose \( a = 0 \) → \( (0 - 1)(0 - 2) = 2 > 0 \) (True) - For \( 1 < a < 2 \): Choose \( a = 1.5 \) → \( (1.5 - 1)(1.5 - 2) = -0.25 < 0 \) (False) - For \( a > 2 \): Choose \( a = 3 \) → \( (3 - 1)(3 - 2) = 2 > 0 \) (True) Thus, the solution for this inequality is: \[ a < 1 \quad \text{or} \quad a > 2 \] ### Step 5: Analyze the second condition The second condition is: \[ |z + i\sqrt{2}| < a \] This represents the distance from \( z \) to the point \( -i\sqrt{2} \). For this distance to be less than \( a \), we need \( a > 0 \). ### Step 6: Combine the conditions From the first condition, we have: 1. \( a < 1 \) or \( a > 2 \) From the second condition, we have: 2. \( a > 0 \) ### Step 7: Determine the valid intervals Combining these conditions: - From \( a < 1 \) and \( a > 0 \), we get \( 0 < a < 1 \). - From \( a > 2 \), we have \( a > 2 \). Thus, the final solution is: \[ a \in (0, 1) \cup (2, \infty) \] ### Step 8: Conclusion The values of \( a \) that satisfy both conditions are: \[ \text{At least one value of } a \text{ must be in } (0, 1) \cup (2, \infty) \]
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OBJECTIVE RD SHARMA-COMPLEX NUMBERS -Exercise
  1. If n is a positive integer greater than unity z is a complex number sa...

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  2. If n is a positive integer greater than unity z is a complex number sa...

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  3. If at least one value of the complex number z=x+iy satisfies the condi...

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  4. Given z is a complex number with modulus 1. Then the equation [(1+i a)...

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  5. The center of a regular polygon of n sides is located at the point z=0...

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  6. If the points z(1),z(2),z(3) are the vertices of an equilateral triang...

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  7. For any complex number z, the minimum value of |z|+|z-1|

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  8. The inequality |z-4| < |z-2| represents

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  9. Number of non-zero integral solution of the equation |1-i| ^(n)=2^(n),...

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  10. If "Im"(2z+1)/(iz+1)=-2, then locus of z, is

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  11. lf z(!=-1) is a complex number such that [z-1]/[z+1] is purely imagina...

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  12. If x=-5+2sqrt(-4) , find the value of x^4+9x^3+35 x^2-x+4.

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  13. If z(1),z(2), z(3) are vertices of an equilateral triangle with z(0) i...

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  14. If z1,z2 are two complex numbers such that Im(z1+z2)=0,Im(z1z2)=0, the...

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  15. If z^2+z|z|+|z^2|=0, then the locus z is a. a circle b. a straight ...

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  16. If log sqrt(3)((|z|^(2)-|z|+1)/(2+|z|))gt2, then the locus of z is

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  17. Let g(x) and h(x) are two polynomials such that the polynomial P(x) =g...

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  18. If g(x) and h(x) are two polynomials such that the polynomials P(x)=g(...

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  19. If |z(1)|=|z(2)|=|z(3)| and z(1)+z(2)+z(3)=0, then z(1),z(2),z(3) are ...

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  20. If x(n)=cos(pi/3^(n))+isin((pi)/(3^(n))), then x(1),x(2),x(3),……………….....

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