integration: int [ x cos(x^2 + 1) ] dx

[dopey9]

can anyone integrate

integrate x*cos(x^2 +1)

so far i got ; (1/2)*sin(x^2 + 1) - the integral of sin(x^2 +1) /2t (this is using the integration by parts formula), now i have to integrate sin(x^2 +1) /2t, this is where i got stuck....im going right so far? can some one help me thankz

 

[mark07]

Before integration by parts, look for an easy way out: u-substitution...

Have you tried u = x^2 + 1 ?

 

[pka]

Re: integration

integrate x*cos(x^2 +1)
so far i got ; (1/2)*sin(x^2 + 1)

Stop right there! You have the answer!

 

[dopey9]

thankz

thankz i got part of that answer from integration by parts but i didnt finish that...and tried the integration by substitution which worked and was easier thankz