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Thread: Elimination Techniques

  1. #1
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    Elimination Techniques

    Hey Guys, I am having troubles with the last 2 questions:

    1. Eliminate t to give an equation that relates x and y:

    $\displaystyle x=e^{2t}$ and $\displaystyle y=e^{7t}+5$

    The main problem is, I don't quite understand what they are asking for. I THINK, you would solve for t and then plug in t for y?

    Such as:
    $\displaystyle ln(x)=2t$

    So, I would plug this into Y to get:

    $\displaystyle y=e^\frac{7}{2}ln(x)$

    ** That lnx should be in the exponent as well**

    Thoughts/comments?

    2.
    Eliminate t to give an equation that relates x and y:
    $\displaystyle x=tan(t), y=sec^2(t)-4$

    Again, I applied the same principles as above and got this:

    $\displaystyle sec^2*atan(x)-4$

    Both answers are wrong but I don't see how else you can interpret these questions.

    Confused.
    Last edited by mr fantastic; Jul 23rd 2009 at 06:51 PM. Reason: Fixed latex in Question 1 (but the OP will have to confirm that these are the correct equations).
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  2. #2
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    Quote Originally Posted by mvho View Post
    1. Eliminate t to give an equation that relates x and y:

    hopefully these equations you attempted to post are correct ...

    $\displaystyle x=e^{2t}$

    $\displaystyle y=e^{7t}+5$


    2.
    Eliminate t to give an equation that relates x and y:

    $\displaystyle x=\tan(t)$

    $\displaystyle y=\sec^2(t)-4$
    1. $\displaystyle y = (e^{2t})^\frac{7}{2} + 5$

    $\displaystyle y = x^\frac{7}{2} + 5$


    2. $\displaystyle y = (1 + \tan^2{t}) - 4$

    $\displaystyle y = (1 + x^2) - 4$
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  3. #3
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    Thanks skeeter. I can see how you solved the equation now.

    I find the wording a little bit tricky.
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