# Integration

• Jun 24th 2008, 01:59 AM
deragon999
Integration

1) find integrate 4x/(x^2+2x+5) dx

I got 2ln((x+1)^2+4) -2Arctan((x+1)/2) +C

2) find integrate (2x^3-4x^2-15x+5)/(x^2-2x-8) dx by partial fractions and long division

I got x^2 +1.5ln(x-4) -0.5ln(x+2) +C

3) integrate lnx/x dx

I got 0.5(lnx)^2 +C

4) integrate cosxln(sinx) dx

I got sinxln(sinx) -sinx +C

Any changes are appreciated and yes to ll is even more appreciated
• Jun 24th 2008, 03:44 AM
topsquark
Quote:

Originally Posted by deragon999

1) find integrate 4x/(x^2+2x+5) dx

I got 2ln((x+1)^2+4) -2Arctan((x+1)/2) +C

2) find integrate (2x^3-4x^2-15x+5)/(x^2-2x-8) dx by partial fractions and long division

I got x^2 +1.5ln(x-4) -0.5ln(x+2) +C

3) integrate lnx/x dx

I got 0.5(lnx)^2 +C

4) integrate cosxln(sinx) dx

I got sinxln(sinx) -sinx +C

Any changes are appreciated and yes to ll is even more appreciated

These are all correct.

You do realize you can check your work by taking the derivative of the answer?

-Dan