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If alpha, beta , gamma are the zeros of ...

If `alpha, beta , gamma` are the zeros of the polynomial `x^(3)-6x^(2)-x+30` then the value of `(alpha beta+beta gamma+gamma alpha)` is

A

`-1 `

B

1

C

`-5`

D

30

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of \( \alpha \beta + \beta \gamma + \gamma \alpha \) for the polynomial \( x^3 - 6x^2 - x + 30 \), we can use Vieta's formulas, which relate the coefficients of a polynomial to sums and products of its roots. ### Step-by-Step Solution: 1. **Identify the coefficients of the polynomial:** The given polynomial is \( x^3 - 6x^2 - x + 30 \). We can identify the coefficients as follows: - Coefficient of \( x^3 \) (let's call it \( a \)): \( 1 \) - Coefficient of \( x^2 \) (let's call it \( b \)): \( -6 \) - Coefficient of \( x \) (let's call it \( c \)): \( -1 \) - Constant term (let's call it \( d \)): \( 30 \) 2. **Apply Vieta's Formulas:** According to Vieta's formulas for a cubic polynomial \( ax^3 + bx^2 + cx + d = 0 \): - The sum of the roots \( \alpha + \beta + \gamma = -\frac{b}{a} = -\frac{-6}{1} = 6 \) - The sum of the products of the roots taken two at a time \( \alpha \beta + \beta \gamma + \gamma \alpha = \frac{c}{a} = \frac{-1}{1} = -1 \) - The product of the roots \( \alpha \beta \gamma = -\frac{d}{a} = -\frac{30}{1} = -30 \) 3. **Conclusion:** Thus, the value of \( \alpha \beta + \beta \gamma + \gamma \alpha \) is \( -1 \). ### Final Answer: The value of \( \alpha \beta + \beta \gamma + \gamma \alpha \) is \( -1 \).
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Knowledge Check

  • If alpha, beta, gamma are the zeros of the polynomial x^(3)-6x^(2) -x+ 30 then (alpha beta+beta gamma + gamma alpha) = ?

    A
    ` -1`
    B
    1
    C
    `-5`
    D
    30
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    ` -3`
    B
    `3`
    C
    `(-1)/2`
    D
    `(-13)/2`
  • If alpha, beta, gamma are the zeros of the polynomial p(x) = 6x^(3)+3x^(2)-5x+1, find the value of (1/alpha+1/beta+1/gamma).

    A
    5
    B
    6
    C
    3
    D
    1
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