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If alpha,beta are the roots of x^(2) + p...

If `alpha,beta` are the roots of `x^(2) + px - q =0 and lambda, delta x^(2) + px - q =0 and lambda, delta " are the roots of " x^(2) - px + r=0 " then what is " (beta + lamda) (beta +delta)` equal to ?

A

`p+r`

B

`p+q`

C

`q+r`

D

`p-q`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \((\beta + \lambda)(\beta + \delta)\) given the roots of two quadratic equations. ### Step-by-Step Solution: 1. **Identify the first quadratic equation**: The first equation is given as: \[ x^2 + px - q = 0 \] The roots of this equation are \(\alpha\) and \(\beta\). 2. **Use Vieta's formulas for the first equation**: By Vieta's formulas, we know: - The sum of the roots \(\alpha + \beta = -\frac{b}{a} = -\frac{p}{1} = -p\) - The product of the roots \(\alpha \beta = \frac{-q}{1} = -q\) 3. **Identify the second quadratic equation**: The second equation is given as: \[ x^2 - px + r = 0 \] The roots of this equation are \(\lambda\) and \(\delta\). 4. **Use Vieta's formulas for the second equation**: Again, applying Vieta's formulas: - The sum of the roots \(\lambda + \delta = -\frac{-p}{1} = p\) - The product of the roots \(\lambda \delta = \frac{r}{1} = r\) 5. **Expand \((\beta + \lambda)(\beta + \delta)\)**: We want to find: \[ (\beta + \lambda)(\beta + \delta) = \beta^2 + \beta\delta + \beta\lambda + \lambda\delta \] 6. **Substitute known values**: From Vieta's formulas: - We know \(\lambda + \delta = p\) - We know \(\lambda \delta = r\) Thus, we can rewrite the expression: \[ = \beta^2 + \beta(\lambda + \delta) + \lambda\delta \] \[ = \beta^2 + \beta p + r \] 7. **Find \(\beta^2\)**: We can express \(\beta^2\) using the first equation. From the first equation: \[ \beta^2 = -p\beta - q \] 8. **Substitute \(\beta^2\) into the expression**: Substituting \(\beta^2\) into our earlier expression: \[ = (-p\beta - q) + \beta p + r \] The \(\beta p\) terms cancel out: \[ = -q + r \] 9. **Final expression**: Therefore, we have: \[ (\beta + \lambda)(\beta + \delta) = r - q \] ### Conclusion: The value of \((\beta + \lambda)(\beta + \delta)\) is: \[ \boxed{r - q} \]

To solve the problem, we need to find the value of \((\beta + \lambda)(\beta + \delta)\) given the roots of two quadratic equations. ### Step-by-Step Solution: 1. **Identify the first quadratic equation**: The first equation is given as: \[ x^2 + px - q = 0 ...
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NDA PREVIOUS YEARS-POLYNOMIAL,QUADRATIC EQUATION & INEQUALITIES-Math
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