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If alpha, beta are zeroes of the polynom...

If `alpha, beta` are zeroes of the polynomial f(x) = `ax^(2)` + bx + c, the c, then `(1)/(alpha^(2))+ (1)/(beta^(2))` =

A

`(b^(2) -2 ac)/(a^(2))`

B

`(b^(2) - 2ac)/(c^(2))`

C

`(b^(2)+2ac)/(a^(2))`

D

`(b^(2) + 2ac)/(c^(2))`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( \frac{1}{\alpha^2} + \frac{1}{\beta^2} \) given that \( \alpha \) and \( \beta \) are the zeroes of the polynomial \( f(x) = ax^2 + bx + c \). ### Step-by-Step Solution: 1. **Start with the expression**: \[ \frac{1}{\alpha^2} + \frac{1}{\beta^2} \] 2. **Find a common denominator**: \[ \frac{1}{\alpha^2} + \frac{1}{\beta^2} = \frac{\beta^2 + \alpha^2}{\alpha^2 \beta^2} \] 3. **Use the identity for \( \alpha^2 + \beta^2 \)**: We know that: \[ \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta \] From Vieta's formulas, we have: \[ \alpha + \beta = -\frac{b}{a} \quad \text{and} \quad \alpha\beta = \frac{c}{a} \] Therefore: \[ \alpha^2 + \beta^2 = \left(-\frac{b}{a}\right)^2 - 2\left(\frac{c}{a}\right) \] Simplifying this gives: \[ \alpha^2 + \beta^2 = \frac{b^2}{a^2} - \frac{2c}{a} = \frac{b^2 - 2ac}{a^2} \] 4. **Substituting back into the expression**: Now substitute \( \alpha^2 + \beta^2 \) back into our expression: \[ \frac{\beta^2 + \alpha^2}{\alpha^2 \beta^2} = \frac{\frac{b^2 - 2ac}{a^2}}{\alpha^2 \beta^2} \] 5. **Calculate \( \alpha^2 \beta^2 \)**: We know: \[ \alpha \beta = \frac{c}{a} \implies \alpha^2 \beta^2 = \left(\frac{c}{a}\right)^2 = \frac{c^2}{a^2} \] 6. **Final expression**: Substitute \( \alpha^2 \beta^2 \) into the expression: \[ \frac{\frac{b^2 - 2ac}{a^2}}{\frac{c^2}{a^2}} = \frac{b^2 - 2ac}{c^2} \] Thus, the final result is: \[ \frac{1}{\alpha^2} + \frac{1}{\beta^2} = \frac{b^2 - 2ac}{c^2} \]
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