Quadratic Equation


Direction: In each of the following question, there are two equations. you have to solve both equations and give answer.

  1. x2 - 16 = 0 y2 - 9y + 20 = 0











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    x2 - 16 = 0
    ⇒ x2 = 16 ⇒ x = √16 = ± 4
    and y2 - 9y + 20 = 0
    y2 - 4y - 5y + 20 = 0
    ⇒ y(y - 4) - 5(y - 4) = 0
    ⇒ y = 5, 4
    ⇒ y ≥ x or x ≤ y

    Correct Option: D

    x2 - 16 = 0
    ⇒ x2 = 16 ⇒ x = √16 = ± 4
    and y2 - 9y + 20 = 0
    y2 - 4y - 5y + 20 = 0
    ⇒ y(y - 4) - 5(y - 4) = 0
    ⇒ y = 5, 4
    ⇒ y ≥ x or x ≤ y


  1. x2 - 32 = 112; y - √169 = 0











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    x2 - 32 = 112
    ⇒ x2 = 112 + 32 ⇒ x2 = 144
    ∴ x = ± 12
    and y - √169 = 0
    ⇒ y = √169
    ⇒ y = ± 13
    ∴ Relation cannot be established.

    Correct Option: E

    x2 - 32 = 112
    ⇒ x2 = 112 + 32 ⇒ x2 = 144
    ∴ x = ± 12
    and y - √169 = 0
    ⇒ y = √169
    ⇒ y = ± 13
    ∴ Relation cannot be established.



  1. x2 - 8x + 15 = 0 ; y2 - 3y + 2 = 0











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    x2 - 8x + 15 = 0
    ⇒ x2 - 5x - 3x + 15 = 0
    ⇒ x(x - 5) -3(x - 5) = 0
    ⇒ (x - 5) (x - 3) = 0
    ∴ x = 5, 3
    and y2 - 3y + 2 = 0
    ⇒ y2 - 2y - y + 2 = 0
    ⇒ y(y - 2) -1(y - 2) = 0
    ⇒ (y -2) (y - 1) = 0
    ⇒ y = 2, 1
    ∴ x > y

    Correct Option: A

    x2 - 8x + 15 = 0
    ⇒ x2 - 5x - 3x + 15 = 0
    ⇒ x(x - 5) -3(x - 5) = 0
    ⇒ (x - 5) (x - 3) = 0
    ∴ x = 5, 3
    and y2 - 3y + 2 = 0
    ⇒ y2 - 2y - y + 2 = 0
    ⇒ y(y - 2) -1(y - 2) = 0
    ⇒ (y -2) (y - 1) = 0
    ⇒ y = 2, 1
    ∴ x > y


  1. x2 - x - 12 = 0; y2 + 5y + 6 = 0











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    Find the value of x and y

    Correct Option: B

    x2 - x - 12 = 0
    ⇒ x2 - 4x + 3x - 12 = 0
    ⇒ x(x - 4) + 3 (x - 4) = 0
    ⇒ (x - 4) (x + 3) = 0
    ∴ x = - 3, 4
    and y2 + 5y + 6 = 0
    ⇒ y2 + 3y + 2y + 6 = 0
    ⇒ y(y + 3) + 2(y + 3) = 0
    ⇒ (y + 3) (y + 2) = 0
    ⇒ y = - 3, - 2
    ∴ x ≥ y
    [∵ x = - 3 and y = - 3, so x = y and x = 4 and y = - 2, hence x > y]



  1. 3x2 + 8x + 4 = 0; 4y2 - 19y + 12 = 0











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    3x2 + 8x + 4 = 0
    ⇒ 3x2 + 6x + 2x + 4 = 0
    ⇒ 3x(x + 2) + 2(x + 2) = 0
    ⇒ (x + 2) (3x + 2) = 0
    ∴ x = - 2, - 2/3
    and 4y2 - 19y + 12 = 0
    ⇒ 4y2 - 16y - 3y + 12 = 0
    ⇒ 4y(y - 4) -3(y - 4) = 0
    ⇒ (y - 4) (4y - 3) = 0
    ∴ y = 4, 3/4
    Hence, y > x or x < y

    Correct Option: C

    3x2 + 8x + 4 = 0
    ⇒ 3x2 + 6x + 2x + 4 = 0
    ⇒ 3x(x + 2) + 2(x + 2) = 0
    ⇒ (x + 2) (3x + 2) = 0
    ∴ x = - 2, - 2/3
    and 4y2 - 19y + 12 = 0
    ⇒ 4y2 - 16y - 3y + 12 = 0
    ⇒ 4y(y - 4) -3(y - 4) = 0
    ⇒ (y - 4) (4y - 3) = 0
    ∴ y = 4, 3/4
    Hence, y > x or x < y