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If alpha ne beta but alpha^(2)= 5 alp...

If ` alpha ne beta ` but ` alpha^(2)= 5 alpha - 3 ` and ` beta ^(2)= 5 beta -3 ` then the equation having ` alpha // beta and beta // alpha ` as its roots is :

A

` 3 x^(2) - 19 x +3=0`

B

`3x^(2) + 19x -3 =0`

C

`3x^(2) - 19x -3 =0`

D

`x^(2) - 5x +3 =0 `

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the equation that has roots \( \frac{\alpha}{\beta} \) and \( \frac{\beta}{\alpha} \). We start with the equations given for \( \alpha \) and \( \beta \): 1. \( \alpha^2 = 5\alpha - 3 \) 2. \( \beta^2 = 5\beta - 3 \) ### Step 1: Rearranging the equations We can rearrange both equations: - From the first equation: \( \alpha^2 - 5\alpha + 3 = 0 \) - From the second equation: \( \beta^2 - 5\beta + 3 = 0 \) ### Step 2: Subtract the two equations Subtract the first equation from the second: \[ \beta^2 - \alpha^2 = 5\beta - 5\alpha \] Factoring both sides gives: \[ (\beta - \alpha)(\beta + \alpha) = 5(\beta - \alpha) \] Since \( \alpha \neq \beta \), we can divide both sides by \( \beta - \alpha \): \[ \beta + \alpha = 5 \] ### Step 3: Add the two equations Now, add the two equations: \[ \alpha^2 + \beta^2 = 5\alpha + 5\beta - 6 \] Using the fact that \( \alpha + \beta = 5 \): \[ \alpha^2 + \beta^2 = 5(5) - 6 = 25 - 6 = 19 \] ### Step 4: Finding \( \alpha \beta \) We know: \[ \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta \] Substituting the known values: \[ 19 = 25 - 2\alpha\beta \] Rearranging gives: \[ 2\alpha\beta = 25 - 19 = 6 \quad \Rightarrow \quad \alpha\beta = 3 \] ### Step 5: Forming the required equation The roots of the equation are \( \frac{\alpha}{\beta} \) and \( \frac{\beta}{\alpha} \). The sum of the roots is: \[ \frac{\alpha}{\beta} + \frac{\beta}{\alpha} = \frac{\alpha^2 + \beta^2}{\alpha\beta} = \frac{19}{3} \] The product of the roots is: \[ \frac{\alpha}{\beta} \cdot \frac{\beta}{\alpha} = 1 \] ### Step 6: Writing the quadratic equation Using the standard form \( x^2 - (sum \ of \ roots)x + (product \ of \ roots) = 0 \): \[ x^2 - \frac{19}{3}x + 1 = 0 \] Multiplying through by 3 to eliminate the fraction: \[ 3x^2 - 19x + 3 = 0 \] ### Final Answer Thus, the required equation is: \[ \boxed{3x^2 - 19x + 3 = 0} \]
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