Evaluate the indefinite integral. (Remember to use ln(abs(u)) where appropriate.)
Follow Math Help Forum on Facebook and Google+
Originally Posted by Jgirl689 Evaluate the indefinite integral. (Remember to use ln(abs(u)) where appropriate.) $\displaystyle \int{\frac{e^{9x}}{e^{9x} + 3}\,dx} = \frac{1}{9}\int{\frac{9e^{9x}}{e^{9x} + 3}\,dx}$. Now make the substitution $\displaystyle u = e^{9x}$ in the denominator.
u = e^9x (1/9) du = e^9x dx int((1 / u + 3)du) ln|u + 3| ln|e^9x + 3| + C
Originally Posted by Locke u = e^9x (1/9) du = e^9x dx int((1 / u + 3)du) ln|u + 3| ln|e^9x + 3| + C Correct. But since $\displaystyle e^{9x} > 0$ for all $\displaystyle x$, you don't need the absolute value.
I put that in my answer thing, and it was marked wrong, should I use log instead?
View Tag Cloud