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Thread: Quadratic Parabola equations

  1. #31
    Senior Member
    Join Date
    Feb 2004
    Ottawa, Ontario
    Quote Originally Posted by LaaLa View Post
    If there was a rating for each person on this website I would give you the top 5 stars! I am so grateful thank you.
    He sure deserves it after that beauty of a solution...
    I'm a man of few words...but I use 'em often!!

  2. #32
    Full Member
    Join Date
    Apr 2015
    Quote Originally Posted by LaaLa View Post
    … All the websites you have mentioned have been visited …
    Alright, but I was thinking not of visits but starting at the beginning of a structured presentation of basic algebra. Learning the concepts in beginning algebra will require a few months of watching lectures and working practice exercises. Continuing to learn the concepts in intermediate algebra will require a few additional months of study.

    … don't want to go too far learning something that isn't part of my study.
    What is your area of study?

    If you're learning math, it's best to gain general knowledge in all the introductory topics. If you try to "specialize" (or your correspondence authors do), and seek out only information that pertains to some tasks at hand, you're really cheating yourself (or being cheated) of the big picture. Math instruction builds upon itself; the general skills you learn in one topic become tools in your toolkit for learning subsequent topics.

    The form used in the example is:
    y= ax^2 + b
    a = 18m (which is half of the base measurement)
    b = 8.5m (vertex)

    put it together...
    y= 18^2 + 8.5
    I think Dr. Peterson already told you that example is not good for this exercise. Also, you did not "put it together" correctly.

    If you're given a generic form of y = ax^2 + b and you're told that a=18 and b=8.5, then the substitution of those values looks like this:

    y = 18x^2 + 8.5

    That's the wrong equation, for the parabolic roof.

    This is why it's better to use a structured approach; learn the general formula which works for any parabola that opens upward or downward:

    y = ax^2 + bx + c

    It seems like your materials might be trying to present some sort of "if the problem looks like this, then do it this way; or if the problem looks like that, then do it that way; or if the problem looks like a third situation, then do it a third way" sort of system. Creating extra rules/shortcuts to cover different situations is unnecessary, when there's a general approach that works in all situations. Why learn different rules for different situations, when there's a general approach that works in all cases?

    I am not doing a class but a correspondence course. It's a self-study … the [materials] are poorly written … [but taking this course] saves you about 600 bucks …
    The online algebra courses and the review sites that I mentioned are FREE. The only expense is your time. It takes several months of study and practice, to gain a strong, complete foundation in algebra -- a foundation that's an essential pre-requisite for studying calculus. (A complete introduction to calculus requires also trigonometry and a handful of pre-calculus topics.) Again, I don't know why you're studying math, but if your goals require a lot of it, you'll save time in the long run by completing a structured course of study prepared by professional mathematicians and educators.
    Last edited by Otis; 01-16-2019 at 02:09 AM. Reason: some added detail regarding algebra study


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