- A= 1
- B= 4
- C= 4
- D= 4
View written solutionFree
Correct answer: B, D
Step-by-Step Solution:
-
Understand the Complex Number Condition: The given condition is
arg((z + α) / (z + β)) = π / 4. Using the property of arguments,arg(w₁ / w₂) = arg(w₁) - arg(w₂), we can rewrite the condition as: -
Convert to Cartesian Coordinates: Let the complex number
zbe represented by the point(x, y), soz = x + iy. Sinceαandβare real numbers, we have:z + α = (x + α) + iyz + β = (x + β) + iyLet
θ₁ = arg(z + α)andθ₂ = arg(z + β). The condition isθ₁ - θ₂ = π / 4. In terms ofxandy:tan(θ₁) = y / (x + α)tan(θ₂) = y / (x + β) -
Derive the Locus Equation: We take the tangent of the argument difference: Using the tangent subtraction formula,
tan(A - B) = (tan A - tan B) / (1 + tan A tan B): {{y \over {x + α}} - {y \over {x + β}}} \over {1 + \left( {y \over {x + α}} \right)\left( {y \over {x + β}} \right)}} = 1 Simplifying the numerator and denominator: This simplifies to: Rearranging the terms, we get the equation of a circle: -
Compare with the Given Circle Equation: The problem states that the ordered pair
(x, y)lies on the circlex² + y² + 5x - 3y + 4 = 0. This means the locus we derived is identical to the given circle. We can compare the coefficients of the two equations:Comparing the coefficients, we get a system of equations:
α + β = 5-(β - α) = -3=>β - α = 3αβ = 4
-
Solve for α and β: We have a system of two linear equations for
αandβ:α + β = 5β - α = 3Adding these two equations gives:2β = 8=>β = 4Substitutingβ = 4into the first equation:α + 4 = 5=>α = 1 -
Verify the Solution: Let's check if these values satisfy the third equation
αβ = 4:(1)(4) = 4. The values are consistent. So, we have uniquely determinedα = 1andβ = 4. -
Evaluate the Options: Now we check each statement with the values
α = 1andβ = 4.- A:
α = -1: This is FALSE becauseα = 1. - B:
αβ = 4: This is TRUE because(1)(4) = 4. - C:
αβ = -4: This is FALSE. - D:
β = 4: This is TRUE.
- A:
Conclusion:
The correct statements are B and D.
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