Quadratic Equation


  1. If one root of the quadratic equation 2x2 + Px + 4 = 0 is 2, find the second root and value of P.









  1. View Hint View Answer Discuss in Forum

    Here ,The given equation is 2x2 + Px + 4 = 0 .......( ⅰ )
    ⇒ P(x) = 0 , where P(x) = 2 2 + Px + 4 = 0
    If 2 is a root of P(x) = 0, then P(2) = 0
    Putting x = 2 in equation ( ⅰ ) , we get
    ⇒ 2(2)2 + P(2) + 4 = 0
    ⇒ 8 + 2P + 4 = 0
    ⇒ 2P = - 12

    P =
    -12
    = - 6
    2

    Correct Option: A

    Here ,The given equation is 2x2 + Px + 4 = 0 .......( ⅰ )
    ⇒ P(x) = 0 , where P(x) = 2 2 + Px + 4 = 0
    If 2 is a root of P(x) = 0, then P(2) = 0
    Putting x = 2 in equation ( ⅰ ) , we get
    ⇒ 2(2)2 + P(2) + 4 = 0
    ⇒ 8 + 2P + 4 = 0
    ⇒ 2P = - 12

    P =
    -12
    = - 6
    2
    Hence the given equation is
    2x2 - 6x + 4 = 0 { ∴ Putting the value of P in eq. ( ⅰ ) }
    ⇒ 2x2 - 2x - 4x + 4 = 0
    ⇒ 2x ( x - 1 ) - 4( x - 1 ) = 0
    ⇒ 2( x - 2 ) ( x - 1 ) = 0
    ⇒ x = 1 or x = 2
    Hence second root is 1.


Direction: In the following questions two equations numbered I and II are given. You have to solve both the equations and give answer
( 1 ) if x > y
( 2 ) if x ≥ y
( 3 ) if x < y
( 4 ) if x ≤ y
( 5 ) if x = y or the relationship cannot be established.

  1. Ⅰ. x2 - 1 = 0
    Ⅱ. y2 + 4y + 3 = 0











  1. View Hint View Answer Discuss in Forum

    From the given equations , we know that
    Ⅰ. x2 - 1 = 0
    ⇒ x2 = 1

    Ⅱ. y2 + 4y + 3 = 0
    ⇒ y2 + y + 3y + 3 = 0
    ⇒ y( y + 1) + 3( y + 1) = 0

    Correct Option: B

    From the given equations , we know that
    Ⅰ. x2 - 1 = 0
    ⇒ x2 = 1
    ⇒ x = ± √1 = ± 1
    Ⅱ. y2 + 4y + 3 = 0
    ⇒ y2 + y + 3y + 3 = 0
    ⇒ y( y + 1) + 3( y + 1) = 0
    ⇒ ( y + 1) ( y + 3)
    ⇒ y = -3 or -1
    From above equations it is clear that x ≥ y is correct answer .



  1. Ⅰ. x3 - 371 = 629
    Ⅱ. y3 - 543 = 788











  1. View Hint View Answer Discuss in Forum

    According to given question , we have
    Ⅰ. x3 - 371 = 629
    ⇒ x = √1000 = 10
    Ⅱ. y3 - 543 = 788
    ⇒ y = √1331 = 11

    Correct Option: C

    According to given question , we have
    Ⅰ. x3 - 371 = 629
    ⇒ x = √1000 = 10
    Ⅱ. y3 - 543 = 788
    ⇒ y = √1331 = 11
    From above both equations it is clear that x < y is correct answer .


  1. Ⅰ. 2x2 + 11x + 12 = 0
    Ⅱ. 5y2 + 27y + 10 = 0











  1. View Hint View Answer Discuss in Forum

    According to question ,we can say that
    From equation Ⅰ. 2x2 + 11x + 12 = 0
    ⇒ 2x2 + 8x + 3x + 12 = 0
    ⇒ 2x( x + 4) + 3( x + 4) = 0

    From equation Ⅱ. 5y2 + 27y + 10 = 0
    ⇒ 5y2 + 25y + 2y + 10 = 0
    ⇒ 5y( y + 5 ) + 2( y + 5 ) = 0

    Correct Option: E

    According to question ,we can say that
    From equation Ⅰ. 2x2 + 11x + 12 = 0
    ⇒ 2x2 + 8x + 3x + 12 = 0
    ⇒ 2x( x + 4) + 3( x + 4) = 0
    ⇒ ( 2x + 3) ( x + 4) = 0

    ∴ x = -
    3
    or, - 4
    2
    From equation Ⅱ. 5y2 + 27y + 10 = 0
    ⇒ 5y2 + 25y + 2y + 10 = 0
    ⇒ 5y( y + 5 ) + 2( y + 5 ) = 0
    ⇒ ( 5y + 2 ) ( y + 5 ) = 0
    ∴ y = -
    2
    or, - 5
    5
    Hence , required answer will be x = y .



  1. Ⅰ. x4 – 227 = 398
    Ⅱ. y2 + 321 = 346











  1. View Hint View Answer Discuss in Forum

    According to question ,we can say that
    From equation Ⅰ. x4 = 398 + 227 = 625

    From equation Ⅱ. y2 = 346 - 321 = 25

    Correct Option: E

    According to question ,we can say that
    From equation Ⅰ. x4 = 398 + 227 = 625
    ⇒ x4 = 54

    From equation Ⅱ. y2 = 346 - 321 = 25
    ⇒ y2 = 52