Recent content by skippenmydesig

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    MHB Is f Integrable and What Is the Limit of the Riemann Sum?

    We only have the epsilon-delta definition to work with for these. Prove that f is integrable and verify the value. On [0,1] f(x)=1 if x=1/2 else 0. $$\int_{0}^{1} \,f$$ =0 Prove: If f is integrable on [0,1] then $$\lim_{{n}\to{\infty}}\ \frac{1}{n} \sum_{k=1}^{n} f(\frac{k}{n})$$ =...
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    If 0<x<y and 0<a<b then ax<yb proof.

    Would this be reasonable: Since a<b mean b-a is positive then x(b-a)<y(b-a) by axiom. then I get xb-xa<yb-ya then because of this definition of < and the face all the terms are positive get xa<xb<ya<yb and from there that xa<yb.
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    If 0<x<y and 0<a<b then ax<yb proof.

    We have but since we are working in only the positive natural numbers for these proofs there are no multiplicative inverses. So far I know the relations ax<ay and bx<by hold. As does ax+bx<ay+by. I've been trying to find a way to add/multiply them so that I can find one that will show ax<by.
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    If 0<x<y and 0<a<b then ax<yb proof.

    Nope, I'm still going in circles :(
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    If 0<x<y and 0<a<b then ax<yb proof.

    By knowing ay-ax is positive and by-bx is positive is there a way to add/multiply that is going to show yb-xa is positive?
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    If 0<x<y and 0<a<b then ax<yb proof.

    We have not defined division so I don't know for sure I could use y/x. I know that ax>0 and by>0 by closure under addition for positive numbers. But I still can't find a way to link ax and yb so that ax<yb.
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    If 0<x<y and 0<a<b then ax<yb proof.

    Do you mean for (1) If x<y then x+z<y+z? If so I've been using both of those and we were told we can use anything else we've already proved as well. I still don't see a way to get the ax<by using just those two axioms or the other properties we have.
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    If 0<x<y and 0<a<b then ax<yb proof.

    I need the formal proof. It's easy enough to know intuitively but I can't seem to find what's going to make it work for the proof.
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    If 0<x<y and 0<a<b then ax<yb proof.

    I think I'm supposed to be able to do it off the definition we have of x<y mean y-x is positive. So I was able to easily do 0<x<y and 0<a<b mean x+a<y+b. I've tried writing everything I can think of that follows from multiplying various ways but I can't seem to get just ax or yb without...
  10. S

    If 0<x<y and 0<a<b then ax<yb proof.

    I need to prove that If 0<x<y and 0<a<b then ax<yb. I've been stuck going in circles for a while now and think I'm missing something really obvious.
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