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If 3+4i is a root of equation x^(2)+px+q...

If 3+4i is a root of equation `x^(2)+px+q=0` where `p, q in R` then

A

p=6, q=25

B

p=6, q=-25

C

p= -6, q= -7

D

p= -6, q=25

Text Solution

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The correct Answer is:
To solve the problem, we need to find the values of \( p \) and \( q \) in the quadratic equation \( x^2 + px + q = 0 \) given that \( 3 + 4i \) is a root. Since the coefficients \( p \) and \( q \) are real numbers, the complex conjugate \( 3 - 4i \) must also be a root. ### Step-by-Step Solution: 1. **Identify the Roots**: Let \( \alpha = 3 + 4i \) and \( \beta = 3 - 4i \). 2. **Find the Sum of the Roots**: The sum of the roots \( \alpha + \beta \) is calculated as follows: \[ \alpha + \beta = (3 + 4i) + (3 - 4i) = 3 + 4i + 3 - 4i = 6 \] 3. **Calculate \( p \)**: According to Vieta's formulas, \( p \) is the negative of the sum of the roots: \[ p = -(\alpha + \beta) = -6 \] 4. **Find the Product of the Roots**: The product of the roots \( \alpha \beta \) is calculated using: \[ \alpha \beta = (3 + 4i)(3 - 4i) = 3^2 - (4i)^2 = 9 - (-16) = 9 + 16 = 25 \] 5. **Calculate \( q \)**: According to Vieta's formulas, \( q \) is equal to the product of the roots: \[ q = \alpha \beta = 25 \] 6. **Final Values**: Thus, we have found: \[ p = -6 \quad \text{and} \quad q = 25 \] ### Conclusion: The values of \( p \) and \( q \) are \( p = -6 \) and \( q = 25 \).
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