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If the product of the roots of the equat...

If the product of the roots of the equation `x^(2)-5kx+2e^("ln|k|")-1=0` is 49, then the sum of the squares of the roots of the equation is :

A

1524

B

1152

C

1244

D

1654

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AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will follow the reasoning provided in the video transcript. ### Step 1: Identify the given quadratic equation The given quadratic equation is: \[ x^2 - 5kx + (2e^{\ln |k|} - 1) = 0 \] ### Step 2: Use the properties of roots of a quadratic equation For a quadratic equation of the form \( ax^2 + bx + c = 0 \), the sum of the roots \( \alpha + \beta \) and the product of the roots \( \alpha \beta \) can be expressed as: - Sum of the roots: \( \alpha + \beta = -\frac{b}{a} \) - Product of the roots: \( \alpha \beta = \frac{c}{a} \) In our case: - \( a = 1 \) - \( b = -5k \) - \( c = 2e^{\ln |k|} - 1 \) Thus, we have: - \( \alpha + \beta = -\frac{-5k}{1} = 5k \) - \( \alpha \beta = \frac{2e^{\ln |k|} - 1}{1} = 2e^{\ln |k|} - 1 \) ### Step 3: Simplify the product of the roots We know from the problem statement that the product of the roots \( \alpha \beta = 49 \). Therefore, we can set up the equation: \[ 2e^{\ln |k|} - 1 = 49 \] ### Step 4: Solve for \( k \) Rearranging the equation gives: \[ 2e^{\ln |k|} = 50 \] \[ e^{\ln |k|} = 25 \] Using the property \( e^{\ln x} = x \), we have: \[ |k| = 25 \] Thus, \( k^2 = 625 \). ### Step 5: Find the sum of the squares of the roots The sum of the squares of the roots can be calculated using the identity: \[ \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta \] Substituting the values we found: - \( \alpha + \beta = 5k \) - \( \alpha \beta = 49 \) Now substituting these into the identity: \[ \alpha^2 + \beta^2 = (5k)^2 - 2 \cdot 49 \] \[ = 25k^2 - 98 \] ### Step 6: Substitute \( k^2 \) into the equation We already found \( k^2 = 625 \). Thus: \[ \alpha^2 + \beta^2 = 25 \cdot 625 - 98 \] \[ = 15625 - 98 \] \[ = 15527 \] ### Final Answer The sum of the squares of the roots is: \[ \boxed{15527} \]
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