Recent content by valmancer

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    Messed up joules and Newtons in an exam

    I know this is just a piece of whining, but I feel awful about it and want other's opinions. It wouldn't really bother if I didn't think I'm OK in physics. In a question I had to calculate potential energy and naturally wrote the answer down as joules. However, when I came back to check the...
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    Continuation of composite function problem problematic

    Thank you once again Bearded Man, I finished the question. The only thing missing is some justification for the formula used (sum of series=...), but I understand if you don't have time to explain why it works.
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    Continuation of composite function problem problematic

    Thank you for the answer Bearded Man, I understand everything else but the an term you use. What does a1 mean? Why is it equal to 1 in my problem?
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    Continuation of composite function problem problematic

    I'm afraid we haven't done anything with sequences or series yet. That's why I think I'm doing something fundamentally wrong :). Could there be another way of doing this question? It would be great if someone could point me to someplace where I can learn about sequences and series and...
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    Continuation of composite function problem problematic

    Thanks for the answer, I thought of them like that almost immediately after writing them down, but still can't get them into any other form. I understand that the exponent is always one more until it reaches n-1. I don't know how I can simplify a^n+a^m, which I think is needed here.
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    Continuation of composite function problem problematic

    I asked about the first part of this problem in https://www.physicsforums.com/showthread.php?t=592408. I thought the best idea was to start another thread for the second part. Homework Statement Part a) Given f(x)=ax+b, and f(3)(x)=64x+21, find the values of the constants a and b. (note...
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    How Do You Solve a Composite Function Problem with Constants?

    Thanks a lot; I don't understand how I didn't notice that. This is how I got the answer in case anyone's interested: a^3x+(a^2b+ab+b)=64x+21 Therefore a^3=64 => a=4 a^2b+ab+b=21 => b(4^2+4+1)=21 => b=21/21=1 Thank you
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    How Do You Solve a Composite Function Problem with Constants?

    Given f(x)=ax+b, and f(3)(x)=64x+21, find the values of the constants a and b. (note: f(3)(x) means fff(x)) To me this seems like I have to use two equations to find the value of three variables, since when I have found a and b, I should be able to get the value of x. Even though it...