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Homework Help: Question on substitution

  1. Nov 5, 2007 #1
    1. The problem statement, all variables and given/known data
    prove by substitution that definite integral int (1/t)dt from [x to x*y] = int (1/t)dt from [1 to y].

    2. Relevant equations

    3. The attempt at a solution
    i can do this problem if i integrate and use the log laws, no probs, but the question says to use a substitution, ive tried many but to no avail, a push in the right direction would be greatly appreciated. Ive asked yesterday about a similar question, which thanks to the forums help i understand. this is the last one on the section and then ill be confident that i can put it rest.
  2. jcsd
  3. Nov 5, 2007 #2


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    Science Advisor
    Homework Helper

    Try the obvious, u=t/x.
  4. Nov 5, 2007 #3
    thks very much, ive learnt more of these two questions, than the previous easier 30.
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