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3+4i is a root of x^(2) + Ax + B = 0 and...

`3+4i` is a root of `x^(2) + Ax + B = 0` and `sqrt(3) -2` is a root of `x^(2) + Cx + D = 0` then

A

a) `A lt Clt D lt B`

B

b) `A lt D lt C lt B`

C

c) `A gt C gt D gt B`

D

d) `A gt D gt C gt B`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the values of \( A \), \( B \), \( C \), and \( D \) based on the given roots of the quadratic equations. Let's go through the steps systematically. ### Step 1: Determine the value of \( A \) and \( B \) Given that \( 3 + 4i \) is a root of the equation \( x^2 + Ax + B = 0 \), we know that the other root must be its conjugate, \( 3 - 4i \), because the coefficients of the polynomial are rational. #### Sum of roots: The sum of the roots \( (3 + 4i) + (3 - 4i) = 6 \). Using Vieta's formulas: \[ A = -\text{(sum of roots)} = -6 \] #### Product of roots: The product of the roots is given by: \[ (3 + 4i)(3 - 4i) = 3^2 - (4i)^2 = 9 - (-16) = 9 + 16 = 25 \] Thus, \[ B = \text{(product of roots)} = 25 \] ### Step 2: Determine the value of \( C \) and \( D \) Now, we have the root \( \sqrt{3} - 2 \) for the equation \( x^2 + Cx + D = 0 \). The other root must be \( -\sqrt{3} - 2 \). #### Sum of roots: The sum of the roots \( (\sqrt{3} - 2) + (-\sqrt{3} - 2) = -4 \). Using Vieta's formulas: \[ C = -\text{(sum of roots)} = 4 \] #### Product of roots: The product of the roots is given by: \[ (\sqrt{3} - 2)(-\sqrt{3} - 2) = -(\sqrt{3} - 2)(\sqrt{3} + 2) = -((\sqrt{3})^2 - 2^2) = -(3 - 4) = -(-1) = 1 \] Thus, \[ D = \text{(product of roots)} = 1 \] ### Step 3: Summary of values Now we have: - \( A = -6 \) - \( B = 25 \) - \( C = 4 \) - \( D = 1 \) ### Step 4: Arrange the values Now we can arrange \( A \), \( B \), \( C \), and \( D \) in ascending order: \[ A < D < C < B \] This gives us: \[ -6 < 1 < 4 < 25 \] ### Conclusion The correct order is \( A < D < C < B \).
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