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Math Help - finding x intercept and completing the square

  1. #1
    Newbie white's Avatar
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    Exclamation finding x intercept and completing the square

    find x-intercepts

    y=(x-1)squared + 2

    y= (x+1)squared -1

    completing the square

    2xsquare -4x +1 =0
    3xsquare - 5x -2=0


    thank you
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  2. #2
    Senior Member nikhil's Avatar
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    Put y=0 and obtian the values of x
    2) 2x^2-4x+1=0
    divd both sides by 2
    x^2-2x+1/2=0
    add one on both sides
    x^2-2x+1/2+1=1
    (x-1)^2+1/2=1
    (x-1)^2=1/2
    do other similarly
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  3. #3
    Super Member
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    Quote Originally Posted by white View Post
    find x-intercepts

    y=(x-1)squared + 2

    y= (x+1)squared -1

    completing the square

    2xsquare -4x +1 =0
    3xsquare - 5x -2=0


    thank you
    y=(x-1)^2 + 2
    y=x^2 -2x +3
    b^2 - 4ac = (-2)^2 - 4(1)(3) = 4-12 = -8 < 0
    The discriminant is less than 0 which means that it does not cross the x-axis hence you won't have x-intercepts.
    Try the other equation yourself by checking the discriminant for the nature of the curve. If it's greater than or equal to zero then it will have x-intercepts. To find it, make y equal to 0 and solve for x.

    2x^2 - 4x+1=0
    For quadratic equations in the form:
    ax^2+bx+c
    The general rule to completing the square is:
    a\left(x + \frac{b}{2a}\right)^2 - \frac{b^2}{4a}  + c
    Use this rule to complete the square for your equations.
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