Recent content by johnnyboy2005

  1. J

    Can i get some help with this integral

    from negative infinity to infinity (1/ 4x^2 + 4x +5) dx is there a way to simplify with partial fracitons or should i do something else? thanks for the help.
  2. J

    Calculating Work Done by a Steam Engine Using Integral Calculus

    it's okay...i figured out where i went wrong
  3. J

    Calculating Work Done by a Steam Engine Using Integral Calculus

    anyone...?
  4. J

    Calculating Work Done by a Steam Engine Using Integral Calculus

    this is a question about a steam engine with the equation (sorry for lack of proper math language) PV^1.4 = k (constant) using the idea of integral from V1 to V2 ie... the amount of work done is W=(int.V1 to V2) PdV Where P1=160lbs/in^2 and V1 = 100 in^3...V2=800 in^3...
  5. J

    What is the difference between integrating by substitution and by parts?

    1/15*x^15 +1/3*x^12 + 2/3*x^9 + 2/3*x^6 + 1/3*x^3 is the value i got from maple 1/15 (1+x^3)^5 is the value i got by hand... plug in values of x...u get different results... if x=1... the first one u get 31/15...the second is 32/15
  6. J

    What is the difference between integrating by substitution and by parts?

    integration by parts?? just trying to figure out this integral int(x^2 (1+x^3)^4 dx) when i integrate by substitution i get anti deriv... 1/15 (1+x^3)^5 which is not the same (but close when u plug in values of x) to 1/15*x^15 +1/3*x^12 + 2/3*x^9 + 2/3*x^6 + 1/3*x^3 am i going about...
  7. J

    Take the anti derivative of (X^2)/sqrt(1-x)soln'let u=1-x

    yeah...that's what i was getting but it was in a different form. Thanks a lot !1
  8. J

    Take the anti derivative of (X^2)/sqrt(1-x)soln'let u=1-x

    take the anti derivative of (X^2)/sqrt(1-x) soln'... let u=1-x... then -du=dx and x^2 = (1-u)^2 (sub back in)... this gives me -2*u^(1/2)*(15-10*u+3*u^2) /15... (sorry for lack of proper terms) anyway, this turns out to be wrong...where did i go wrong here?
  9. J

    Graduate Is It Possible to Identify an Original Isomorphism in Group Theory?

    If an group G is isomorphic to a group G(prime) then they are only equal or approximately equal. If this can continue on, i.e. G(prime) is isomorphic to a group W... then we are not sure if G is the original group. Is it possible to find a group that is an original isomorphism? Does this...
  10. J

    Proving Automorphism of Z_n with r in U(n)

    it is an isomorphism because it is one to one and onto...
  11. J

    Proving Automorphism of Z_n with r in U(n)

    so i actually left this question for a bit. This is my soln' so far... to show it is an automorphism the groups must be one to one and onto (easy to show) and to show that the function is map preserving I'm saying that for any a and b in Z(n) you will have (alpha)(a+b) = (alpha)(a) +...
  12. J

    Undergrad What Is the Difference Between Isomorphisms and Homomorphisms?

    i was just wondering if someone (matt) could give me a better idea of what the difference is between the two...thanks
  13. J

    Undergrad Cyclic Abelian Groups: True for All Cases?

    yes. other wise my question answers itself. so cyclic implies abelian. thanks for the help.
  14. J

    Undergrad Cyclic Abelian Groups: True for All Cases?

    is this true for all cases? i know something can be abelian and not cyclic. thanks
  15. J

    Proving the Necessity of Commutativity for Automorphisms in Groups

    this is what I'm saying so far since everyelement in G is mapped to it's inverse, and since the following is true alpha(ab)-->(ab)^-1 --->(ba)^-1-->alpha(ba) then G must be abelian for this to be true. ...make sense or am i missing something?