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Question: How can I plot a*x^2 + b*x + c

Question:How can I plot a*x^2 + b*x + c

wpd 56 Maple
May 12 2008
0
<p>I apologize if this seems quite basic, but that's the point where I am in learning about Maple.  I would like to define a function, take its derivative, plot it, divide it by its derivative, plot that result, etc...</p>
<p>For example: f(x) = a*x^2 + b*x + c</p>
<p>From what I've learned so far, I think I do this to define the function:</p>
<p>f := x -> a*x^2+b*x+c</p>
<p>I also seem to have learned that:</p>
<p>diff(f, x)</p>
<p>doesn't do what I want, but</p>
<p>diff(f(x),x)</p>
<p>does.  Now I'm at the point where I would like to plot my function, using some sort of nominal values for a, b, and c.  I think I can do something like:</p>
<p>a:=123</p>
<p>b:=456</p>
<p>c:=789</p>
<p>plot(f(x),x=0..1000)</p>
<p>but now a, b, and c are defined in my workspace so that</p>
<p>diff(f(x),x)</p>
<p>gives me</p>
<p>246x + 456</p>
<p>instead of the</p>
<p>2ax + b</p>
<p>that I got previously.  Is there some way to "fix" the constants of an equasion when plotting them without having them be set for the rest of my document?</p>
<p>I'm sorry if this sounds confusing, it's only because I'm confused.  :-)</p>
<p> </p>
<p>Thanks.</p>
<p>--wpd</p>
<p> </p>
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