Home
Class 11
MATHS
For each parabola y=x^(2)+px+q, meeting ...

For each parabola `y=x^(2)+px+q`, meeting coordinate axes at 3-distinct points, if circles are drawn through these points, then the family of circles must pass through

A

(1, 0)

B

(0, 1)

C

(1, 1)

D

(p, q)

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we need to analyze the parabola and the circles formed by the intersection points with the coordinate axes. Let's break it down: ### Step 1: Identify the Parabola The given parabola is: \[ y = x^2 + px + q \] ### Step 2: Find Intersection Points with the Axes 1. **Intersection with the x-axis**: Set \( y = 0 \): \[ 0 = x^2 + px + q \] This quadratic equation has roots \( \alpha \) and \( \beta \) (the x-intercepts). By Vieta's formulas: - Sum of roots: \( \alpha + \beta = -p \) - Product of roots: \( \alpha \beta = q \) 2. **Intersection with the y-axis**: Set \( x = 0 \): \[ y = 0^2 + p \cdot 0 + q = q \] Thus, the intersection point with the y-axis is \( (0, q) \). ### Step 3: Define the Points of Intersection The points of intersection with the axes are: - \( A(\alpha, 0) \) - \( B(\beta, 0) \) - \( C(0, q) \) ### Step 4: Equation of the Circle through Points A, B, and C The general equation of a circle passing through three points \( A(x_1, y_1) \), \( B(x_2, y_2) \), and \( C(x_3, y_3) \) is given by: \[ x^2 + y^2 + 2gx + 2fy + c = 0 \] Substituting the points \( A, B, \) and \( C \) into this equation will yield a system of equations. ### Step 5: Substitute Points into the Circle Equation 1. For point \( A(\alpha, 0) \): \[ \alpha^2 + 2g\alpha + c = 0 \quad \text{(1)} \] 2. For point \( B(\beta, 0) \): \[ \beta^2 + 2g\beta + c = 0 \quad \text{(2)} \] 3. For point \( C(0, q) \): \[ q^2 + 2fq + c = 0 \quad \text{(3)} \] ### Step 6: Solve the System of Equations Subtract equation (2) from equation (1): \[ \alpha^2 - \beta^2 + 2g(\alpha - \beta) = 0 \] Factoring gives: \[ (\alpha - \beta)(\alpha + \beta + 2g) = 0 \] Since \( \alpha \neq \beta \), we have: \[ \alpha + \beta + 2g = 0 \implies g = -\frac{p}{2} \] Next, add equations (2) and (3): \[ \beta^2 + q^2 + 2g(\beta) + 2fq + 2c = 0 \] Substituting \( g = -\frac{p}{2} \) and simplifying will yield a relationship between \( f \) and \( q \). ### Step 7: Final Relationship After manipulating the equations, we find: \[ c = q \quad \text{and} \quad f = \frac{q + 1}{2} \] ### Step 8: Family of Circles Substituting \( g, f, \) and \( c \) back into the circle equation gives: \[ x^2 + y^2 - \frac{p}{2}x + \frac{q + 1}{2}y + q = 0 \] ### Conclusion The family of circles passes through the point \( (0, 1) \) as verified by substituting \( x = 0 \) and \( y = 1 \) into the final equation.

To solve the problem step by step, we need to analyze the parabola and the circles formed by the intersection points with the coordinate axes. Let's break it down: ### Step 1: Identify the Parabola The given parabola is: \[ y = x^2 + px + q \] ### Step 2: Find Intersection Points with the Axes 1. **Intersection with the x-axis**: Set \( y = 0 \): ...
Promotional Banner

Topper's Solved these Questions

  • PARABOLA

    OBJECTIVE RD SHARMA ENGLISH|Exercise SECTION-I (SOLVED MCQs EXAMPLE)|1 Videos
  • PARABOLA

    OBJECTIVE RD SHARMA ENGLISH|Exercise Section II - Assertion Reason Type|7 Videos
  • PARABOLA

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|30 Videos
  • PAIR OF STRAIGHT LINES

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|18 Videos
  • PERMUTATIONS AND COMBINATIONS

    OBJECTIVE RD SHARMA ENGLISH|Exercise Chapter Test|60 Videos

Similar Questions

Explore conceptually related problems

P(a,5a) and Q(4a,a) are two points. Two circles are drawn through these points touching the axis of y. Centre of these circles are at

If the lines 2x+3y+1=0, 6x+4y+1=0 intersect the co-ordinate axes in 4 points, then the circle passing through the points is

If a tangent to the circle x^(2)+y^(2)=1 intersects the coordinate axes at distinct points P and Q, then the locus of the mid-point of PQ is :

Find the equations of the circles passing through the point (-4,3) and touching the lines x+y=2 and x-y=2

Find the equations of the circles passing through the point (-4,3) and touching the lines x+y=2 and x-y=2

Let P be the family of parabolas y=x^2+p x+q ,(q!=0), whose graphs cut the axes at three points. The family of circles through these three points have a common point (1, 0) (b) (0, 1) (c) (1, 1) (d) none of these

The circle passing through the point (-1,0) and touching the y-axis at (0,2) also passes through the point:

The line x = y touches a circle at the point (1, 1). If the circle also passes through the point (1, -3). Then its radius is 0

Show that the circle x^(2)+ y^(2) - 4x + 4y + 4 = 0 touches the co-ordinate axes. If the points of contact are A and B, find the equation of the circle which passes through A, B and the origin,

Obtain the differential equation of the family of circles passing through the point (a,0) and (-a,0).

OBJECTIVE RD SHARMA ENGLISH-PARABOLA-Section I - Solved Mcqs
  1. The locus of the midpoint of the segment joining the focus to a moving...

    Text Solution

    |

  2. The radical centre of the circles drawn on the focal chords of y^(2)=4...

    Text Solution

    |

  3. For each parabola y=x^(2)+px+q, meeting coordinate axes at 3-distinct ...

    Text Solution

    |

  4. Let A(x(1),y(1)) and B(x(2),y(2)) be two points on the parabola y^(2) ...

    Text Solution

    |

  5. Let A and B be two distinct points on the parabola y^2=4x. If the ax...

    Text Solution

    |

  6. the shortest distance between the line y-x=1 and the curve x=y^(2) ...

    Text Solution

    |

  7. about to only mathematics

    Text Solution

    |

  8. Let PQ be a focal chord of the parabola y^(2)=4ax. The tangents to the...

    Text Solution

    |

  9. Let a, r, s, t be non-zero real numbers. Let P(at^(2),2at),Q(ar^(2),2a...

    Text Solution

    |

  10. Let a, r, s, t be non-zero real numbers. Let P(at^(2),2at),Q(ar^(2),2a...

    Text Solution

    |

  11. Let P and Q be distinct points on the parabola y^2 = 2x such that a c...

    Text Solution

    |

  12. about to only mathematics

    Text Solution

    |

  13. PSQ is a focal chord of a parabola whose focus is S and vertex is A. P...

    Text Solution

    |

  14. Let P be the point on the parabola y^(2)4x which is at the shortest di...

    Text Solution

    |

  15. Let P be the point on the parabola, y^(2)=8x which is at a minimum dis...

    Text Solution

    |

  16. P and Q are two distinct points on the parabola, y^2 = 4x with paramet...

    Text Solution

    |

  17. Let PQ be a focal chord of the parabola y^(2)=4x. If the centre of a c...

    Text Solution

    |

  18. The centres of those circles which touch the circle, x^(2)+y^(2)-8x-8y...

    Text Solution

    |

  19. The radius of a circle, having minimum area, which touches the curve...

    Text Solution

    |

  20. If a chord , which is not a tangent of the parabola y^2=16x has the eq...

    Text Solution

    |