Posted by **Jane** on Sunday, November 27, 2011 at 6:19pm.

Use integration by parts to find the integral. Round the answer to two decimal places if necessary. (x+4) ln x dx between 3 and 0.

I tried this problem two different ways and got two different answers 1.63 and 3.89. which one is correct? Please.

- Calculus -
**Steve**, Sunday, November 27, 2011 at 6:45pm
u = ln x

du = 1/x dx

dv = (x+4) dx

v = x^2/2 + 4x

Int[(x+4)ln x dx] = (x^2/2 + 4x)lnx - Int(x/2 + 4)dx

= (x^2/2 + 4x)lnx - (x^2/4 + 4x)

Evaluating over the interval, we get

[9/2 + 12)ln3 - (9/4 + 12)] - [0]

= 33/2 ln3 - 57/4

= 3.8771

- Calculus -
**Jane**, Sunday, November 27, 2011 at 6:48pm
same thing I got, but not even close to any of the answer choices ... 2.69, 16.69, -2.15, and 1.51. This one has me stumped!!

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