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Find t given:

$$0.715+258.115e^{-0.5t}-67.83e^{-0.25t}=0$$

Please help. I've substituted $e^{-0.5t}$ for $x$ and did

$$-67.83x^2+258.115x+0.715=0$$

but the answer is not coming out? Am I doing something wrong because it doesn't follow the quadratic rule?

Mark Viola
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Grace
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1 Answers1

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If you let $e^{-0.25t} = k$

The equation then becomes:

$$258.115k^2-67.83k + 0.715 = 0$$

You should be able to solve the above quadratic equation and then find the values of t by solving $e^{-0.25t} = k$.

John_dydx
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