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Maths parabola minimum point?

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    Hi,
    I am a GCSE maths student, and I need some help with a parabola minimum point question I was doing for revision.
    When a question asks 'find the minimum point' and gives you the equation of the parabola, what do you do after you complete the square?

    For example, the question used the equation x squared - 8x +23

    I then wrote this out as (x-4) squared + 7

    Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?
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    (Original post by katesimpson2112)
    Hi,
    I am a GCSE maths student, and I need some help with a parabola minimum point question I was doing for revision.
    When a question asks 'find the minimum point' and gives you the equation of the parabola, what do you do after you complete the square?

    For example, the question used the equation x squared - 8x +23

    I then wrote this out as (x-4) squared + 7

    Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?
    Almost, check the sign on your x-value.

    The smallest value (x-4)2 can take is zero, since squared numbers are always positive. So you can immediately see that the minimum point, y=7, will be where the squared bracket is zero, i.e: where x-4=0.

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    So do you mean that:
    If x-4=0, then x=4 ? And y=7?
    Sorry, I just get a tad frustrated due to my slightly incompetant teacher who didn't finish teaching us the syllabus :L
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    (Original post by katesimpson2112)
    So do you mean that:
    If x-4=0, then x=4 ? And y=7?
    Sorry, I just get a tad frustrated due to my slightly incompetant teacher who didn't finish teaching us the syllabus :L
    Yes.

    (Original post by katesimpson2112)
    Hi,

    Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?
    They're both the same equation just written differently so will produce the same result.
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    Thanks, both of you!

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