Form an equation with roots α/β and β/α: Given that α and β are roots of 2x^2 − 3x + 1 = 0, form the quadratic equation whose roots are α/β and β/α.

Difficulty: Medium

Correct Answer: 2x^2 − 5x + 2 = 0

Explanation:


Introduction / Context:
Transforming roots often relies on expressing new symmetric sums in terms of the old. If α and β satisfy a known quadratic, we can compute α + β and αβ, then find (α/β) + (β/α) and (α/β)(β/α) to construct the desired equation.

Given Data / Assumptions:

  • Original equation: 2x^2 − 3x + 1 = 0.
  • Hence α + β = 3/2, αβ = 1/2.
  • New roots: r1 = α/β and r2 = β/α.


Concept / Approach:
Compute sum and product of new roots: r1 + r2 = (α^2 + β^2)/(αβ) and r1*r2 = 1. Then use x^2 − (sum)x + (product) = 0 and clear denominators to get integer coefficients.


Step-by-Step Solution:

α^2 + β^2 = (α + β)^2 − 2αβ = (3/2)^2 − 2*(1/2) = 9/4 − 1 = 5/4.Sum r1 + r2 = (α^2 + β^2)/(αβ) = (5/4)/(1/2) = 5/2.Product r1*r2 = 1.Equation: x^2 − (5/2)x + 1 = 0 ⇒ multiply by 2 ⇒ 2x^2 − 5x + 2 = 0.


Verification / Alternative check:
Symmetry implies r1 and r2 are reciprocals; indeed product 1 confirms. Coefficients are integers after clearing denominators.


Why Other Options Are Wrong:

  • 2x^2 + 5x + 2 = 0 or 2x^2 − 5x − 2 = 0: Wrong sign patterns for sum and product.
  • None of these: Incorrect since 2x^2 − 5x + 2 = 0 fits perfectly.


Common Pitfalls:
Miscomputing α^2 + β^2 or forgetting to divide by αβ. Ensure careful fraction arithmetic.


Final Answer:

2x^2 − 5x + 2 = 0

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