Math Problem Statement

यदि α, β तथा γ बहुपद x^3 - x^2 - 10x - 8 के शून्यांक हो तो αβ + βγ + γα + αβγ का मान है—

Solution

The given equation in the image is x3x210x8=0x^3 - x^2 - 10x - 8 = 0, and the question is asking to find the value of αβ+βγ+γα+αβγ\alpha\beta + \beta\gamma + \gamma\alpha + \alpha\beta\gamma, where α\alpha, β\beta, and γ\gamma are the roots of the cubic equation.

Step 1: Understanding the problem

For a cubic equation of the form:

x3+px2+qx+r=0x^3 + px^2 + qx + r = 0

If α\alpha, β\beta, and γ\gamma are the roots, we can use Vieta's formulas:

  • α+β+γ=p\alpha + \beta + \gamma = -p (sum of the roots),
  • αβ+βγ+γα=q\alpha\beta + \beta\gamma + \gamma\alpha = q (sum of the products of the roots taken two at a time),
  • αβγ=r\alpha\beta\gamma = -r (product of the roots).

Step 2: Identifying coefficients

Comparing the given equation x3x210x8=0x^3 - x^2 - 10x - 8 = 0 with the general form, we get:

  • p=1p = -1 (coefficient of x2x^2),
  • q=10q = -10 (coefficient of xx),
  • r=8r = -8 (constant term).

Step 3: Using Vieta’s formulas

From Vieta’s formulas, we know:

  • α+β+γ=(1)=1\alpha + \beta + \gamma = -(-1) = 1,
  • αβ+βγ+γα=10\alpha\beta + \beta\gamma + \gamma\alpha = -10,
  • αβγ=(8)=8\alpha\beta\gamma = -(-8) = 8.

Step 4: Calculating the required expression

The expression we need to find is αβ+βγ+γα+αβγ\alpha\beta + \beta\gamma + \gamma\alpha + \alpha\beta\gamma.

Substituting the values from Vieta’s relations:

αβ+βγ+γα+αβγ=10+8=2.\alpha\beta + \beta\gamma + \gamma\alpha + \alpha\beta\gamma = -10 + 8 = -2.

Final Answer:

The value of αβ+βγ+γα+αβγ\alpha\beta + \beta\gamma + \gamma\alpha + \alpha\beta\gamma is 2-2.

So, the correct option is A: -2.


Let me know if you'd like further details or have any questions!

Here are five related questions:

  1. How does Vieta's formula apply to quadratic equations?
  2. Can Vieta's relations be used for equations of higher degree, and how?
  3. What happens if one of the roots of the cubic equation is zero?
  4. How would the expression change if we were given a quartic equation?
  5. How can we factor a cubic polynomial given its roots?

Tip: Vieta's formulas are a powerful tool for quickly relating the coefficients of a polynomial to its roots without needing to solve the equation explicitly!

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Math Problem Analysis

Mathematical Concepts

Algebra
Polynomials
Cubic Equations

Formulas

Vieta's Formulas
Sum of roots: α + β + γ = -p
Sum of products of roots taken two at a time: αβ + βγ + γα = q
Product of roots: αβγ = -r

Theorems

Vieta's Theorem

Suitable Grade Level

Grades 9-12