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B Making a definite integral equal and indefinite integral?

  1. May 24, 2016 #1
    I have a calculator which allows me to sketch indefinite integrals - it assumes c = 0. However, when I try to use Desmos Online Graphing Calculator, it won't let me do this with it's integral function. It keeps trying to make me use definite integrals.

    I know that ∫(a,b,f(x)dx = F(a) - F(b), so I was wondering if it's possible to define a and b so that the resulting definite integral equals the indefinite integral (where c = 0)
     
  2. jcsd
  3. May 24, 2016 #2

    andrewkirk

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    How does it sketch the definite integrals? If it sketches the curve of ##F(x)## vs ##x## where ##F(x)## is defined as:
    $$F(x)=\int_a^x f(t)dt$$
    then the sketch will be exactly the same as that of an indefinite integral ##G=\int f(x)dx## with zero integration constant, except shifted downwards by ##G(a)##.
     
  4. May 24, 2016 #3
    So if I make a equal to a x-intercept of the indefinite integral of f(x), then
    $$F(x)=\int_a^x f(t)dt$$
    With no shift?
     
  5. May 24, 2016 #4

    andrewkirk

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    Yes, that should work.
     
  6. May 24, 2016 #5
    Thank you! :)
     
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