Thread: Integration

Here a few questions i had solved by the method that was asked for can someone please check my answers:

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

Originally Posted by deragon999

Here a few questions i had solved by the method that was asked for can someone please check my answers:

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