Home
Class 11
MATHS
Given that alpha and beta are the roots ...

Given that `alpha and beta` are the roots of the equation `2x^(2)-3x+4=0`, find an equation whose roots are `alpha+(1)/(alpha) and beta+(1)/(beta)`.

Text Solution

AI Generated Solution

The correct Answer is:
To find an equation whose roots are \( \alpha + \frac{1}{\alpha} \) and \( \beta + \frac{1}{\beta} \), where \( \alpha \) and \( \beta \) are the roots of the equation \( 2x^2 - 3x + 4 = 0 \), we can follow these steps: ### Step 1: Identify the coefficients and roots of the original quadratic equation The given quadratic equation is: \[ 2x^2 - 3x + 4 = 0 \] From this, we can identify: - \( a = 2 \) - \( b = -3 \) - \( c = 4 \) ### Step 2: Calculate the sum and product of the roots Using Vieta's formulas, we know: - The sum of the roots \( \alpha + \beta = -\frac{b}{a} = -\frac{-3}{2} = \frac{3}{2} \) (Equation 1) - The product of the roots \( \alpha \beta = \frac{c}{a} = \frac{4}{2} = 2 \) (Equation 2) ### Step 3: Find the new roots We need to find the new roots: \[ \alpha + \frac{1}{\alpha} \quad \text{and} \quad \beta + \frac{1}{\beta} \] #### Step 3a: Calculate the sum of the new roots The sum of the new roots can be calculated as follows: \[ \left( \alpha + \frac{1}{\alpha} \right) + \left( \beta + \frac{1}{\beta} \right) = (\alpha + \beta) + \left( \frac{1}{\alpha} + \frac{1}{\beta} \right) \] Using the identity \( \frac{1}{\alpha} + \frac{1}{\beta} = \frac{\alpha + \beta}{\alpha \beta} \): \[ \frac{1}{\alpha} + \frac{1}{\beta} = \frac{\frac{3}{2}}{2} = \frac{3}{4} \] Thus, the sum of the new roots becomes: \[ \frac{3}{2} + \frac{3}{4} = \frac{6}{4} + \frac{3}{4} = \frac{9}{4} \] #### Step 3b: Calculate the product of the new roots The product of the new roots is: \[ \left( \alpha + \frac{1}{\alpha} \right) \left( \beta + \frac{1}{\beta} \right) = \alpha \beta + \frac{1}{\alpha \beta} + \frac{\alpha}{\beta} + \frac{\beta}{\alpha} \] Using the identity \( \frac{\alpha}{\beta} + \frac{\beta}{\alpha} = \frac{\alpha^2 + \beta^2}{\alpha \beta} \): \[ \alpha^2 + \beta^2 = (\alpha + \beta)^2 - 2\alpha \beta = \left( \frac{3}{2} \right)^2 - 2 \cdot 2 = \frac{9}{4} - 4 = \frac{9}{4} - \frac{16}{4} = -\frac{7}{4} \] Now substituting back: \[ \alpha \beta + \frac{1}{\alpha \beta} + \frac{\alpha^2 + \beta^2}{\alpha \beta} = 2 + \frac{1}{2} + \frac{-\frac{7}{4}}{2} = 2 + \frac{1}{2} - \frac{7}{8} \] Converting to a common denominator: \[ 2 = \frac{16}{8}, \quad \frac{1}{2} = \frac{4}{8} \quad \Rightarrow \quad \frac{16}{8} + \frac{4}{8} - \frac{7}{8} = \frac{13}{8} \] ### Step 4: Form the new quadratic equation Now we can form the new quadratic equation using the sum and product of the new roots: \[ x^2 - \left( \text{sum of roots} \right)x + \text{product of roots} = 0 \] Substituting the values: \[ x^2 - \frac{9}{4}x + \frac{13}{8} = 0 \] To eliminate the fractions, multiply the entire equation by 8: \[ 8x^2 - 18x + 13 = 0 \] ### Final Answer The equation whose roots are \( \alpha + \frac{1}{\alpha} \) and \( \beta + \frac{1}{\beta} \) is: \[ 8x^2 - 18x + 13 = 0 \]
Promotional Banner

Topper's Solved these Questions

  • QUADRATIC EQUATIONS

    ICSE|Exercise EXERCISE 10 (d)|14 Videos
  • QUADRATIC EQUATIONS

    ICSE|Exercise EXERCISE 10 (e)|4 Videos
  • QUADRATIC EQUATIONS

    ICSE|Exercise EXERCISE 10 (b)|16 Videos
  • PROPERTIES OF TRIANGLE

    ICSE|Exercise EXERCISE 7|38 Videos
  • RELATION AND FUNCTIONS

    ICSE|Exercise MULTIPLE CHOICE QUESTIONS (Choose the correct answer from the given four options in questions)|32 Videos

Similar Questions

Explore conceptually related problems

alpha and beta are the roots of the equation x^(2) - 3x + 5 = 0 , the equation whose roots are (1)/(alpha) and (1)/(beta) is:

If alpha and beta are the roots of the equation 2x^(2)+3x+2=0 , find the equation whose roots are alpha+1 and beta+1 .

If alpha and beta are the roots of the equation 3x^(2) -4x+ 1 =0 ,find the equation whose roots are (alpha^(2))/( beta) and ( beta^(2))/( alpha )

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

If alpha and beta are the roots of the equation 2x^(2)+4x-5=0 , then the equation whose roots are (1)/(2alpha-3) and (1)/(2beta-3) is

If alpha,beta are the roots of the equation x^(2)-3x+4=0 , then the equation whose roots are (alpha-2)/(alpha+2),(beta-2)/(beta+2) is

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

If alpha and beta are the roots of the equation x^(2) + x+ 1 = 0, then what is the equation whose roots are alpha^(19) and beta^(7) ?

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

If alpha,beta are the roots of lthe equation 2x ^2-3x-6=0, find the equation whose roots are alpha^2+2 and beta^2+2.

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 ...

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |