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Given that alpha and beta are the roots ...

Given that `alpha and beta` are the roots of the equation `x^(2)-x+7=0`, find
(i) The numerical value of `(alpha)/(beta+3)+(beta)/(alpha+3)`,
(ii) an equation whose roots are `(alpha)/(beta+3) and (beta)/(alpha+3)`.

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To solve the problem step by step, we will break down the solution into two parts as given in the question. ### Given: The quadratic equation is: \[ x^2 - x + 7 = 0 \] ### Step 1: Find the roots (α and β) Using Vieta's formulas: - The sum of the roots \( \alpha + \beta = -\frac{b}{a} = -\frac{-1}{1} = 1 \) - The product of the roots \( \alpha \beta = \frac{c}{a} = \frac{7}{1} = 7 \) ### Step 2: Calculate \( \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} \) To find this expression, we will first find a common denominator: \[ \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} = \frac{\alpha(\alpha + 3) + \beta(\beta + 3)}{(\beta + 3)(\alpha + 3)} \] Now, simplify the numerator: \[ \alpha(\alpha + 3) + \beta(\beta + 3) = \alpha^2 + 3\alpha + \beta^2 + 3\beta = (\alpha^2 + \beta^2) + 3(\alpha + \beta) \] Using the identity \( \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha\beta \): \[ \alpha^2 + \beta^2 = (1)^2 - 2(7) = 1 - 14 = -13 \] Thus, we have: \[ \alpha^2 + \beta^2 + 3(\alpha + \beta) = -13 + 3(1) = -13 + 3 = -10 \] Now, substituting back into the expression: \[ \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} = \frac{-10}{(\beta + 3)(\alpha + 3)} \] ### Step 3: Calculate \( (\beta + 3)(\alpha + 3) \) Expanding this: \[ (\beta + 3)(\alpha + 3) = \alpha\beta + 3\alpha + 3\beta + 9 = 7 + 3(1) + 9 = 7 + 3 + 9 = 19 \] ### Step 4: Final Calculation Now substituting back: \[ \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} = \frac{-10}{19} \] ### Answer for Part (i): \[ \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} = -\frac{10}{19} \] --- ### Part (ii): Find an equation whose roots are \( \frac{\alpha}{\beta + 3} \) and \( \frac{\beta}{\alpha + 3} \) #### Step 1: Sum of the roots From part (i), we know: \[ \text{Sum} = \frac{\alpha}{\beta + 3} + \frac{\beta}{\alpha + 3} = -\frac{10}{19} \] #### Step 2: Product of the roots Calculating the product: \[ \frac{\alpha}{\beta + 3} \cdot \frac{\beta}{\alpha + 3} = \frac{\alpha\beta}{(\beta + 3)(\alpha + 3)} = \frac{7}{19} \] #### Step 3: Form the quadratic equation Using the standard form \( x^2 - (\text{Sum})x + \text{Product} = 0 \): \[ x^2 + \frac{10}{19}x + \frac{7}{19} = 0 \] Multiplying through by 19 to eliminate the fraction: \[ 19x^2 + 10x + 7 = 0 \] ### Answer for Part (ii): The required quadratic equation is: \[ 19x^2 + 10x + 7 = 0 \] ---
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ICSE-QUADRATIC EQUATIONS-EXERCISE 10 (c)
  1. If the sum of the roots of the equation x^(2)-px+q=0 be m times their ...

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  2. If one root of the equation x^(2)+ax+8=0 is 4 while the equation x^(2)...

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  3. Find the value of a for which one root of the quadratic equation (a^(2...

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  4. If alpha,beta are the roots of the equation ax^(2)-bx+b=0, prove that ...

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  5. If alpha and beta are the roots of the equation x^(2)+x-7=0, form the ...

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  6. If alpha and beta are the roots of the equation 2x^(2)+3x+2=0, find th...

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  7. Find the equation whose roots are (alpha)/(beta) and (beta)/(alpha), w...

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  8. If alpha and beta are the roots of the equation 2x^(2)-3x+1=0, form th...

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  9. If a ne b and a^(2)=5a-3,b^(2)=5b-3, then form that equation whose roo...

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  10. Given that alpha and beta are the roots of the equation x^(2)=x+7. (...

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  11. Given that alpha and beta are the roots of the equation x^(2)-x+7=0, f...

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  12. Given that alpha and beta are the roots of the equation 2x^(2)-3x+4=0,...

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  13. The roots of the quadratic equation x^(2)+px+8=0 are alpha and beta. ...

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  14. If the roots of x^(2)-bx+c=0 be two consecutive integers, then find th...

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  15. The roots of the equation px^(2)-2(p+1)x+3p=0 are alpha and beta. If a...

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  16. The roots of the equation ax^(2)+bx+c=0 are alpha and beta. Form the q...

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  17. Two candidates attempt to solve a quadratic equation of the form x^(2)...

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  18. Given that alpha and beta are the roots of the equation x^(2)=7x+4, ...

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  19. The ratio of the roots of the equation x^(2)+alphax+alpha+2=0 is 2. fi...

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  20. If (1-p) is a root of the quadratic equation x^(2)+px+(1-p)=0, then it...

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