# Homework Help: Integration by parts help

1. Jun 4, 2009

### intelli

1. The problem statement, all variables and given/known data

integral limit 1 to 5

integral of sqrt x * lnx dx

a = 1
b= 5

2. Relevant equations

3. The attempt at a solution

2
x (-1 + 2 Log[x])
------------------
8

11.99604193 but its not right

2. Jun 4, 2009

### rock.freak667

Not sure how you reached that answer but did you use

u=lnx and dv=x1/2 dx ?

3. Jun 4, 2009

### intelli

so is this right

du = 1/x dx

v = 3/2x^3/2

and plug into the parts formula?

4. Jun 4, 2009

### rock.freak667

v=2/3 x3/2

check that back.

then yes put that into the formula.

5. Jun 4, 2009

### intelli

yes so i get this is this right after integrating

2/3 x^3/2 ln x (between limits 1 to 5 ) - 4/9 x^3/2 (between limits 1 to 5) and

i get 9.602

6. Jun 4, 2009

### chriscolose

Your calculus looks correct, but somehow you're not coming up with the right number. Re-check your computations and you should get approximately 7.47.