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if p and q are non zero constants, the equation `x^2+px+q=0` has roots ` alpha` and `beta` then the equation `qx^2+px+1=0` has roots

A

`qx^(2) + px + 1 = 0 "has roots"(1)/(u)and(1)/(v)`

B

`(x-p)(x+q) = 0 "has roots" u + v and uv`

C

`x^(2) + p^(2) x + q^(2) = 0 "has roots" u^(2) and v^(2)`

D

`x^(2) + qx + p = 0"has roots" (u)/(v) and (v)/(u)`

Text Solution

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The correct Answer is:
To solve the problem step by step, we start with the given quadratic equation and its roots. ### Step 1: Understand the given quadratic equation We have the quadratic equation: \[ x^2 + px + q = 0 \] with roots \( \alpha \) and \( \beta \). ### Step 2: Use Vieta's formulas From Vieta's formulas, we know: - The sum of the roots \( \alpha + \beta = -\frac{p}{1} = -p \) - The product of the roots \( \alpha \beta = \frac{q}{1} = q \) ### Step 3: Write the second quadratic equation We need to analyze the second quadratic equation: \[ qx^2 + px + 1 = 0 \] ### Step 4: Substitute the values of \( p \) and \( q \) From the first equation, we have: - \( p = -(\alpha + \beta) \) - \( q = \alpha \beta \) Substituting these into the second equation gives: \[ (\alpha \beta)x^2 - (\alpha + \beta)x + 1 = 0 \] ### Step 5: Rewrite the equation in standard form This can be rearranged as: \[ \alpha \beta x^2 - (\alpha + \beta)x + 1 = 0 \] ### Step 6: Identify the new roots Now we can express this quadratic equation in terms of its roots. The roots of the quadratic equation \( ax^2 + bx + c = 0 \) can be found using Vieta's formulas: - The sum of the roots \( r_1 + r_2 = -\frac{b}{a} \) - The product of the roots \( r_1 r_2 = \frac{c}{a} \) For our equation: - \( a = \alpha \beta \) - \( b = -(\alpha + \beta) \) - \( c = 1 \) Thus, we have: - The sum of the roots \( r_1 + r_2 = \frac{\alpha + \beta}{\alpha \beta} \) - The product of the roots \( r_1 r_2 = \frac{1}{\alpha \beta} \) ### Step 7: Find the roots The roots can be expressed as: \[ r_1 = \frac{1}{\alpha} \quad \text{and} \quad r_2 = \frac{1}{\beta} \] ### Conclusion Thus, the roots of the equation \( qx^2 + px + 1 = 0 \) are: \[ \frac{1}{\alpha} \text{ and } \frac{1}{\beta} \] ---
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OBJECTIVE RD SHARMA ENGLISH-QUADRATIC EXPRESSIONS AND EQUATIONS -Exercise
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  13. If a lt c lt b then the roots of the equation (a−b)x^2 +2(a+b−2c)x+1=0...

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  15. If alpha , beta are roots of ax^(3) +bx +c=0 then the equation ax^...

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  16. If alpha ne beta but alpha^(2)= 5 alpha - 3 and beta ^(2)= 5 beta...

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  19. Given that a x^2+b x+c=0 has no real roots and a+b+c<0, then c!=0 b. c...

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