MHB Evaluating the Improper Integral

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The discussion evaluates the improper integral $$\int ^0_{-\infty} \frac{1}{e^{2x}} \, dx$$ and confirms the steps taken in the calculation. The limit process is applied, leading to the substitution of variables and the evaluation of the integral. The result indicates that the limit diverges to infinity, confirming that the integral does not converge. The final conclusion is that the evaluation of the integral is correct, affirming the divergence. The discussion effectively clarifies the steps involved in handling improper integrals.
shamieh
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Evaluate the Integral.

Just wondering if someone could check my work, thanks in advance.

$$\int ^0_{-\infty} \frac{1}{e^{2x}} \, dx $$

$$lim_{a\to-\infty} \int ^0_a \frac{1}{e^{2x}} \, dx = lim_{a\to-\infty} \frac{1}{2} \int ^0_a \frac{1}{e^u}$$

*Letting $$u = 2x$$
&& $$du/2 = dx$$

$$
\therefore lim_{a\to-\infty} \frac{1}{2} \int ^0_a e^{-u} = lim_{a\to-\infty} \frac{1}{2} \int ^0_{2a} e^{-u}$$

$$= -\frac{1}{2}e^{-u} |^0_{2a}$$

$$= -\frac{1}{2} + \infty $$

$$\therefore$$ as $$ lim_{a\to-\infty}$$ diverges
 
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What you've done is correct :)
 

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