I am having trouble figuring out a step in an example of exponential distribution involving calculus?

Question

sorry I cant figure out notation on this, I have tried to make it as clear as possible: integration = S, >, < upper and lower values of the space, respectivly, e= Eulers number.

S>infinity,<t A*e^-(A*x)dx = -e^-(A*x) between infinity and t = e^(A*t)

I cannot figure out why e becomes negative after the first operation. Also, if you know how to import notation into yahoo answers, I would also really appreciate that.

Answer 1

when you integrate  e^x.....  it&#039;s   derivative of x times e^x plus constant.

so in your example, you have e raised to the   -Ax...   since you have a negative -A  times x, your derivative will be -A wrt x.  That&#039;s how come you get the negatives.

Sorry can&#039;t help you on how to import notations....

good luck