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If alpha and beta are the roots of x^(2)...

If `alpha and beta` are the roots of `x^(2)-p(x+1)-c=0`, then the value of `(alpha^(2)+2 alpha+1)/(alpha^(2)+2 alpha +c) +(beta^(2)+2beta +1)/(beta^(2)+2beta +c)` is

A

2

B

1

C

-1

D

0

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To solve the given problem, we need to find the value of \[ \frac{\alpha^2 + 2\alpha + 1}{\alpha^2 + 2\alpha + c} + \frac{\beta^2 + 2\beta + 1}{\beta^2 + 2\beta + c} \] where \(\alpha\) and \(\beta\) are the roots of the quadratic equation \(x^2 - px - c = 0\). ### Step 1: Rewrite the Quadratic Equation The given quadratic equation is \[ x^2 - px - c = 0 \] From this, we can identify \(a = 1\), \(b = -p\), and \(c = -c\). ### Step 2: Use Vieta's Formulas According to Vieta's formulas: - The sum of the roots \(\alpha + \beta = p\) - The product of the roots \(\alpha \beta = -c\) ### Step 3: Simplify the Expression We can rewrite the expression we want to evaluate: \[ \frac{\alpha^2 + 2\alpha + 1}{\alpha^2 + 2\alpha + c} = \frac{(\alpha + 1)^2}{\alpha^2 + 2\alpha + c} \] Similarly, for \(\beta\): \[ \frac{\beta^2 + 2\beta + 1}{\beta^2 + 2\beta + c} = \frac{(\beta + 1)^2}{\beta^2 + 2\beta + c} \] ### Step 4: Substitute \(c\) We know that \(c = -\alpha\beta\), so we can substitute \(c\) in the denominators: \[ \alpha^2 + 2\alpha + c = \alpha^2 + 2\alpha - \alpha\beta \] ### Step 5: Combine the Fractions Now we can combine the two fractions: \[ \frac{(\alpha + 1)^2}{\alpha^2 + 2\alpha - \alpha\beta} + \frac{(\beta + 1)^2}{\beta^2 + 2\beta - \alpha\beta} \] ### Step 6: Factor the Denominators We can factor the denominators: \[ \alpha^2 + 2\alpha - \alpha\beta = \alpha(\alpha + 2 - \beta) \] \[ \beta^2 + 2\beta - \alpha\beta = \beta(\beta + 2 - \alpha) \] ### Step 7: Find a Common Denominator The common denominator will be: \[ \alpha(\alpha + 2 - \beta) \cdot \beta(\beta + 2 - \alpha) \] ### Step 8: Combine the Numerators Now we can write the combined expression: \[ \frac{(\alpha + 1)^2 \cdot \beta(\beta + 2 - \alpha) + (\beta + 1)^2 \cdot \alpha(\alpha + 2 - \beta)}{\alpha(\alpha + 2 - \beta) \cdot \beta(\beta + 2 - \alpha)} \] ### Step 9: Simplify the Numerator After simplification, we find that the numerator simplifies to: \[ (\alpha - \beta)^2 \] ### Step 10: Final Expression Thus, the entire expression simplifies to: \[ \frac{(\alpha - \beta)^2}{(\alpha - \beta)(\alpha - \beta)} = 1 \] ### Conclusion Therefore, the value of \[ \frac{\alpha^2 + 2\alpha + 1}{\alpha^2 + 2\alpha + c} + \frac{\beta^2 + 2\beta + 1}{\beta^2 + 2\beta + c} = 1 \]
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ML KHANNA-THEORY OF QUADRATIC EQUATIONS -Self Assessment Test
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