MHB Evaluating the Improper Integral

shamieh
Messages
538
Reaction score
0
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
 
Physics news on Phys.org
What you've done is correct :)
 
Back
Top