Home
Class 11
MATHS
Statement (1) : If a and b are integers ...

Statement (1) : If a and b are integers and roots of `x^2 + ax + b = 0` are rational then they must be integers. Statement (2): If the coefficient of `x^2` in a quadratic equation is unity then its roots must be integers

A

Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1.

B

Statement-1 is True, Statement-2 is True, Statement-2 is not a correct explanation for Statement-1.

C

Statement-1 is True, Statement-2 is False.

D

Statement-1 is False, Statement-2 is True.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the given problem, we need to analyze both statements one by one. ### Step-by-Step Solution: **Statement (1):** If \( a \) and \( b \) are integers and the roots of \( x^2 + ax + b = 0 \) are rational, then they must be integers. 1. **Understanding Rational Roots:** - Let the roots of the quadratic equation \( x^2 + ax + b = 0 \) be \( \frac{p}{q} \) and \( \frac{r}{s} \), where \( p, q, r, s \) are integers and \( q, s \neq 0 \). 2. **Using Vieta's Formulas:** - According to Vieta's formulas, the sum of the roots \( \left( \frac{p}{q} + \frac{r}{s} \right) = -a \) and the product of the roots \( \left( \frac{p}{q} \cdot \frac{r}{s} \right) = b \). 3. **Clearing Denominators:** - Multiply the entire equation by \( qs \) (the product of the denominators) to eliminate fractions: \[ ps + qr = -aqs \quad \text{(1)} \] \[ pr = bqs \quad \text{(2)} \] 4. **Analyzing the Equations:** - From equation (1), since \( ps + qr \) is an integer and \( -aqs \) is also an integer, we conclude that \( qs \) must divide \( ps + qr \). - From equation (2), since \( pr \) is an integer, \( qs \) must divide \( bqs \). 5. **Divisibility Implications:** - If \( qs \) divides \( pr \), and since \( q \) and \( s \) are integers, it follows that \( q \) must divide \( p \) and \( s \) must divide \( r \). - Given that the highest common factor (HCF) of \( p \) and \( q \) is 1, it implies that \( q = 1 \) and \( s = 1 \). 6. **Conclusion for Statement (1):** - Therefore, the roots \( \frac{p}{1} \) and \( \frac{r}{1} \) must be integers. Hence, Statement (1) is **True**. --- **Statement (2):** If the coefficient of \( x^2 \) in a quadratic equation is unity, then its roots must be integers. 1. **Consider a Quadratic Equation:** - Let’s take an example of a quadratic equation where the coefficient of \( x^2 \) is 1, such as \( x^2 + x + 1 = 0 \). 2. **Finding the Roots:** - The roots can be found using the quadratic formula: \[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] Here, \( a = 1, b = 1, c = 1 \): \[ x = \frac{-1 \pm \sqrt{1^2 - 4 \cdot 1 \cdot 1}}{2 \cdot 1} = \frac{-1 \pm \sqrt{1 - 4}}{2} = \frac{-1 \pm \sqrt{-3}}{2} \] 3. **Analyzing the Roots:** - The roots are \( \frac{-1 \pm i\sqrt{3}}{2} \), which are complex numbers, not integers. 4. **Conclusion for Statement (2):** - Therefore, it is not necessarily true that if the coefficient of \( x^2 \) is unity, the roots must be integers. Hence, Statement (2) is **False**. ### Final Answer: - Statement (1) is **True**. - Statement (2) is **False**. ---

To solve the given problem, we need to analyze both statements one by one. ### Step-by-Step Solution: **Statement (1):** If \( a \) and \( b \) are integers and the roots of \( x^2 + ax + b = 0 \) are rational, then they must be integers. 1. **Understanding Rational Roots:** - Let the roots of the quadratic equation \( x^2 + ax + b = 0 \) be \( \frac{p}{q} \) and \( \frac{r}{s} \), where \( p, q, r, s \) are integers and \( q, s \neq 0 \). ...
Promotional Banner

Topper's Solved these Questions

  • QUADRATIC EXPRESSIONS AND EQUATIONS

    OBJECTIVE RD SHARMA ENGLISH|Exercise Exercise|138 Videos
  • QUADRATIC EXPRESSIONS AND EQUATIONS

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|50 Videos
  • QUADRATIC EXPRESSIONS AND EQUATIONS

    OBJECTIVE RD SHARMA ENGLISH|Exercise Section I - Solved Mcqs|123 Videos
  • PROBABILITY

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|45 Videos
  • SEQUENCES AND SERIES

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|59 Videos

Similar Questions

Explore conceptually related problems

If a and b are integers then ab is a rational number Check the validity of the statement

Suppose a, b are integers and a + b is a root of x^2 + ax + b = 0 . What is the maximum possible values of b^2 ?

If (1-p) is a root of quadratic equation x^2+p x+(1-p)=0, then find its roots.

If (1-p) is a root of quadratic equation x^2+p x+(1-p)=0, then find its roots.

If a ,b ,a n dc are odd integers, then prove that roots of a x^2+b x+c=0 cannot be rational.

If the roots of x^2-bx +c=0 are two consecutive integers then b^2-4c=

If a, b, c are odd integers, then the roots of ax^(2)+bx+c=0 , if real, cannot be

The roots of the equation x^2+ax+b=0 are

If a and b(!=0) are the roots of the equation x^2+ax+b=0 then the least value of x^2+ax+b is

If a and b are the odd integers, then the roots of the equation, 2ax^2 + (2a + b)x + b = 0, a!=0 , will be

OBJECTIVE RD SHARMA ENGLISH-QUADRATIC EXPRESSIONS AND EQUATIONS -Section II - Assertion Reason Type
  1. If alpha and beta are the roots of the equation x^(2)-ax+b=0and A(n)=a...

    Text Solution

    |

  2. Statement-1: If alpha and beta are real roots of the quadratic equatio...

    Text Solution

    |

  3. Statement-1: If a, b, c, A, B, C are real numbers such that a lt b lt ...

    Text Solution

    |

  4. Statement I: x^2-5x+6<0 if 2 < x < 3 Statement II: If alpha and beta, ...

    Text Solution

    |

  5. about to only mathematics

    Text Solution

    |

  6. Statement-1: There is a value of k for which the equation x^(3) - 3x +...

    Text Solution

    |

  7. Statement-1: If x^(2) + ax + 4 gt 0 "for all" x in R, then a in (-4, 4...

    Text Solution

    |

  8. If the roots of the equation ax^2 + bx + c = 0, a != 0 (a, b, c are re...

    Text Solution

    |

  9. Statement (1) : If a and b are integers and roots of x^2 + ax + b = 0 ...

    Text Solution

    |

  10. Statement-1: If a, b, c are distinct real numbers, then a((x-b)(x-c))/...

    Text Solution

    |

  11. Let f(x)=a x^2+bx +c a ,b ,c in R. If f(x) takes real values for re...

    Text Solution

    |

  12. Statement-1: If a, b, c in R and 2a + 3b + 6c = 0, then the equation a...

    Text Solution

    |

  13. Statement-1: If a ne 0 and the equation ax^(2) + bx + c = 0 has two ro...

    Text Solution

    |

  14. Statement-1: If a, b, c in Q and 2^(1//3) is a root of ax^(2) + bx + c...

    Text Solution

    |

  15. Statement-1: If f(x) = 1 + x + (x^(2))/(2!) + (x^(3))/(3!) + (x^(4))/(...

    Text Solution

    |

  16. Given that for all real x, the expression (x^(2)-2x+4)/(x^(2)+2x+4) l...

    Text Solution

    |

  17. Let a, b, c be real numbers such that ax^(2) + bx + c = 0 and x^(2) + ...

    Text Solution

    |

  18. Statement-1: The cubic equation 4x^(3) - 15x^(2)+14x-5 = 0 has a root ...

    Text Solution

    |

  19. Statement-1: The equation (pi^(e))/(x-e)+(e^(pi))/(x-pi)+(pi^(pi)+e^(e...

    Text Solution

    |

  20. Consider a quadratic equation ax^(2) + bx + c = 0, where 2a + 3b + 6c ...

    Text Solution

    |