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If two roots of x^3 - 9x^2 + 14 x +24...

If two roots of ` x^3 - 9x^2 + 14 x +24 =0` are in the ratio 3:2 then the roots are

A

`6,4,-1`

B

`3,2,4`

C

`1/2,1/3.(49)/(6)`

D

`6,4,2`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the roots of the polynomial equation \( x^3 - 9x^2 + 14x + 24 = 0 \) given that two of the roots are in the ratio \( 3:2 \). ### Step-by-Step Solution: 1. **Assume the Roots**: Let the two roots in the ratio \( 3:2 \) be \( 3k \) and \( 2k \). Let the third root be \( \alpha \). 2. **Use Vieta's Formulas**: According to Vieta's formulas, the sum of the roots of the polynomial \( ax^3 + bx^2 + cx + d = 0 \) is given by: \[ 3k + 2k + \alpha = -\frac{b}{a} \] Here, \( a = 1 \) and \( b = -9 \), so: \[ 5k + \alpha = 9 \] 3. **Find One Root by Trial**: We can try to find one root by substituting values into the polynomial. Let's test \( x = -1 \): \[ (-1)^3 - 9(-1)^2 + 14(-1) + 24 = -1 - 9 - 14 + 24 = 0 \] Hence, \( x = -1 \) is a root, so we can set \( \alpha = -1 \). 4. **Substitute \( \alpha \) into the Sum of Roots**: Now substituting \( \alpha = -1 \) into the sum of roots equation: \[ 5k - 1 = 9 \] Solving for \( k \): \[ 5k = 10 \implies k = 2 \] 5. **Calculate the Roots**: Now we can find the actual roots: - The first root: \( 3k = 3 \times 2 = 6 \) - The second root: \( 2k = 2 \times 2 = 4 \) - The third root: \( \alpha = -1 \) 6. **Final Roots**: Therefore, the roots of the equation \( x^3 - 9x^2 + 14x + 24 = 0 \) are \( 6, 4, \) and \( -1 \). ### Conclusion: The roots of the equation are \( 6, 4, \) and \( -1 \). ---
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