Recent content by Euklidian-Space

  1. E

    ##\left|L(f_{n}, P) - L(f,P)\right| < \epsilon##

    well since ##m_{k}## and ##m_{k}^{'}## are the infs they are definitely bounded by ##\epsilon## if ##|f_n(x) - f(x)|<\varepsilon## for all ##x##; which is true because we have uniform convergence
  2. E

    ##\left|L(f_{n}, P) - L(f,P)\right| < \epsilon##

    what exactly is less than ##\epsilon/2##? I was thinking something like... $$|L(f_{n},P) - L(f,p)| = |\sum_{k = 1}^{n} m_{k}^{'}(x_{k} - x_{k - 1}) - \sum_{k = 1}^{n} m_{k} (x_{k} - x_{k - 1}|$$ we then have $$\sum_{k = 1}^{n} m_{k}^{'} - m_{k} (x_{k} - x_{k - 1})$$ now if i can bound...
  3. E

    ##\left|L(f_{n}, P) - L(f,P)\right| < \epsilon##

    oh my bad. L(f,p) is the lower sum of the Reimann integral $$L(f,P) = \sum_{k = 1}^{n} m_{k} (x_{k} - x_{k - 1})$$
  4. E

    ##\left|L(f_{n}, P) - L(f,P)\right| < \epsilon##

    Homework Statement Suppose that ##f_{n} \rightarrow f## uniformly on [a,b] and that each ##f_{n}## is integrable on [a,b]. Show that given ##\epsilon > 0##, there exists a partition ##P## and a natural number ##N## such that ##\left|L(f_{n}, P) - L(f,P)\right| < \epsilon##. Homework...
  5. E

    If f''(a) exists then f''(a) = ....

    wait how do you get \lim_{h \to 0} \frac{f'(a + h) - f'(a) - hf''(a)}{2h} = \frac{f''(a) - f''(a)}{2} = 0
  6. E

    If f''(a) exists then f''(a) = ....

    Well I tried applying lhopitals again. But I get ##\lim_{n\to0} \frac{f"(a+h) - f"(a-h)}{2}##. Which seems to be a little closer, but not quite.
  7. E

    If f''(a) exists then f''(a) = ....

    ok when i apply l'hopital's i get the following $$\lim_{h \rightarrow 0} \frac{f'(a+h) - f'(a - h)}{2h}$$ we differentiate the numerator and denominator with respect to the limit variable right? doesn't seem like it is giving us ##f''(a) = \lim_{h \to 0} \frac{f''(a + h) - f''(a)}{h}##
  8. E

    If f''(a) exists then f''(a) = ....

    DEvens, would you use the limit definition for differentiation to prove this? If so how would you resolve the different limit variables?
  9. E

    If f''(a) exists then f''(a) = ....

    it seems even with the taylor method you get into the same problem. $$f(a + h) = f(a) + hf'(a) + \frac{1}{2} h^2f''(a) + \epsilon (h)$$ solve for f''(a) and get $$f''(a) = \frac{2f(a + h) - 2f(a) - 2hf'(a) - 2\epsilon (h)}{h^2}$$ so i guess at this point you would take limit of both sides...
  10. E

    If f is even then then left and right integrals are equal

    Again I am sorry man i just don't understand. dy = -dx right? then how does ##\int_{-a}^{0} f(y) dy = \int_{-a}^{0} f(x) dx##? when dy = -dx? I do not see how using a "DUMMY variable" justifies dy = -dx to dy = dx
  11. E

    If f is even then then left and right integrals are equal

    oh sorry, didnt see that. it is fixed now.
  12. E

    If f is even then then left and right integrals are equal

    No that's what i meant... Since dy = -dx we get that negative out in front done we?
  13. E

    If f is even then then left and right integrals are equal

    I am sorry if I am being difficult vela, but I just don't understand why showing $$\int_{0}^{a}f(x)dx = \int_{-a}^{0} f(y) dy$$ shows that $$\int_{0}^{a}f(x)dx = \int_{-a}^{0} f(x) dx$$ if anything i think i have shown... $$\int_{0}^{a} f(x) dx = -\int_{-a}^{0} f(x) dx$$
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