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If the ratio of the roots of x^(2) + bx ...

If the ratio of the roots of `x^(2) + bx + c = 0` is equal to the ratio of the roots of `x^(2)+px+q=0`, then `p^(2)c-b^(2)q=`

A

a) 0

B

b) 1

C

c) 2

D

d) 3

Text Solution

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The correct Answer is:
To solve the problem, we need to find the value of \( p^2c - b^2q \) given that the ratio of the roots of the equations \( x^2 + bx + c = 0 \) and \( x^2 + px + q = 0 \) are equal. ### Step-by-step Solution: 1. **Identify the Roots**: - For the equation \( x^2 + bx + c = 0 \), let the roots be \( \alpha \) and \( \beta \). - The sum of the roots \( \alpha + \beta = -b \). - The product of the roots \( \alpha \beta = c \). - For the equation \( x^2 + px + q = 0 \), let the roots be \( \gamma \) and \( \delta \). - The sum of the roots \( \gamma + \delta = -p \). - The product of the roots \( \gamma \delta = q \). 2. **Set Up the Ratio of Roots**: - We are given that the ratio of the roots of the first equation is equal to the ratio of the roots of the second equation: \[ \frac{\alpha}{\beta} = \frac{\gamma}{\delta} \] 3. **Apply Componendo-Dividendo**: - By applying the Componendo-Dividendo method, we can rewrite the ratio: \[ \frac{\alpha + \beta}{\alpha - \beta} = \frac{\gamma + \delta}{\gamma - \delta} \] 4. **Substitute the Values**: - Substitute the values of the sums and differences of the roots: \[ \frac{-b}{\alpha - \beta} = \frac{-p}{\gamma - \delta} \] 5. **Square Both Sides**: - Squaring both sides gives us: \[ \left(\frac{-b}{\alpha - \beta}\right)^2 = \left(\frac{-p}{\gamma - \delta}\right)^2 \] 6. **Express Differences**: - The differences \( \alpha - \beta \) and \( \gamma - \delta \) can be expressed using the square root of the discriminants: \[ \alpha - \beta = \sqrt{b^2 - 4c}, \quad \gamma - \delta = \sqrt{p^2 - 4q} \] 7. **Substituting Back**: - Now substituting these into the squared ratio: \[ \frac{b^2}{b^2 - 4c} = \frac{p^2}{p^2 - 4q} \] 8. **Cross Multiply**: - Cross multiplying gives: \[ b^2(p^2 - 4q) = p^2(b^2 - 4c) \] 9. **Rearranging the Equation**: - Rearranging the equation leads to: \[ p^2b^2 - 4b^2q = p^2b^2 - 4p^2c \] 10. **Simplifying**: - Cancel \( p^2b^2 \) from both sides: \[ -4b^2q = -4p^2c \] 11. **Final Result**: - Dividing by -4 gives: \[ p^2c - b^2q = 0 \] ### Conclusion: Thus, the value of \( p^2c - b^2q \) is \( 0 \).
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