Neal D. answered • 10/18/16
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X = y2 would be a sideways parabola and therefore not a function.
Good test for function: Vertical Line test. If a vertical line passes thru two points on the graph of a relation, it is NOT a function.
Neal D.
That is not the intention of the problem. In the context of the work being done in the book,
they would be looking at several different equations and graphs, determining which ones
are functions and which ones are not functions. They look at parabolas, circles, ellipses,
hyperbolas, exponential graphs, etc.. There is a build-up of material that leads
to functions being one-to-one. I have never seen a problem where they tried to make the
stipulation that although y is not a function of x, it is true that x is a function of y.
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10/18/16
Mark M.
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I agree with David W. Usually, students deal with functions of the form y = f(x). However, there are certain area and volume problems in Calculus where it is advantageous to treat x as a function of y rather than treating y as a function of x because the integral needed to do the problem where x is a function of y is less complicated than the alternative integral (using y as a function of x).
Mark M (Bayport, NY)
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10/18/16
Neal D.
These problems are being done at the Algebra I level, not Calculus! Work within
the context of the book, otherwise the student will have a difficult time following
what is being stated.
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10/18/16
David W.
Note: When pointing out a problem, suggest a solution. I recommended a very easy, accurate rewording.
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10/18/16
David W.
10/18/16