Question

Can someone help me with this?

Integrate e^x/(e^x+4)

Answer 1

hint!!

let u = e^x

do a u substitution ;)

Answer 2

u = e^x + 4
du = e^x dx

integrate 1/u du ... i think

Answer 3

yup that's right @dedee :)

Answer 4

do you know how to proceed now @Saltin8R ?

Answer 5

not sure how this works do i answer or just help?

Answer 6

Not exactly. Is there a certain rule for integrating 1/u? Coz that's just the same as u^-1, which would integrate to 1.

Answer 7

you just help :) @dedee as much as possible ^_^

Answer 8

yeah it should be listed in the back of your book or on a reference page

Answer 9

yes there is a rule to 1/u

it is the exception to the power rule

\[\int \frac{1}{f(x)} = \ln |f(x)| + c\]

got that @Saltin8R ?

Answer 10

d/dx ln(x) = 1/x =)

Answer 11

the power rule is \[\int f(x)^n = \frac{f(x)^{n+1}}{n+1}\] however..if n would be -1 then the denominator would be 0 garnering undefined..thus u^-1 is the exception

Answer 12

yes, thanks guys :) I've got the correct answer :)

Answer 13

congradumations ^_^