Integration

stanners 27

can anybody help find the definate integral of f(x)=e^(-nx) from 0 to n?
thanks guys :smile:

Reply 1

Mr M

Study Forum Helper

Original post by stanners 27

can anybody help find the definate integral of f(x)=e^(-nx) from 0 to n?
thanks guys :smile:

\displaystyle \int e^{kx} \, dx = \frac{e^{kx}}{k} + c

Reply 2

stanners 27

Original post by Mr M

\displaystyle \int e^{kx} \, dx = \frac{e^{kx}}{k} + c

So that gives (-e^{^}-n²)/n between 0 and n. but then you have to divide by 0.

Reply 3

Kvothe the Arcane

Original post by stanners 27

So that gives (-e^{^}-n²)/n between 0 and n. but then you have to divide by 0.

What? I think you misunderstood.

\displaystyle \int_0^n e^{-nx}dx \neq \left[\dfrac{-e^{-n^2}}{n} \right]_0^n

(edited 10 years ago)

Reply 4

Mr M

Study Forum Helper

Original post by stanners 27

So that gives (-e^{^}-n²)/n between 0 and n. but then you have to divide by 0.

x is zero not n.

Reply 5

stanners 27

Original post by Mr M

x is zero not n.

you have to divide by x, as that is in the indefinateintegral. then replace x with the boundries. Don't you?

Reply 6

stanners 27

Original post by Mr M

x is zero not n.

ahh i see now. i was confused by x and n. thanks. :colondollar:

Reply 7

Mr M

Study Forum Helper

Original post by stanners 27

you have to divide by x, as that is in the indefinateintegral. then replace x with the boundries. Don't you?

No you don't divide by x at any point. Look at my first post carefully. And it's "definite".

Reply 8

Mr M

Study Forum Helper

Original post by stanners 27

ahh i see now. i was confused by x and n. thanks. :colondollar:

It's a fairly common mistake to make if that makes you feel any better!

Reply 9

stanners 27

Original post by Mr M

It's a fairly common mistake to make if that makes you feel any better!

Thanks. I don't suppose you know how to calculate infimum of f(x)=(x^0.5)/
(2+x) do you?

Reply 10

Mr M

Study Forum Helper

Original post by stanners 27

Thanks. I don't suppose you know how to calculate infimum of f(x)=(x^0.5)/
(2+x) do you?

You could sketch the graph.

Quick Reply

Latest

Articles for you

Students react after A-level Maths Paper 3 on 20 June

What is an LLM and how could it benefit your career?

Powerful questions business students forget to ask their career advisers

Why I chose a law degree and what studying law was like

Integration

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you