For some reason, wolfram alpha does not seem to understand integration.http://www.wolframalpha.com/input/?i=(1%2FL)*((integrate+(a_1*x^2%2Ba_2*x%2Ba_3)*(co s(n*pi*x%2FL)+from+-L+to+0)%2B(integrate+(b_1*x^2%2Bb_2*x%2Bb_3)*(cos( n*pi*x%2FL)++from+0+to+L))

Is there a computer algebra system that can integrate

(1/L)*((integrate (a_1*x^2+a_2*x+a_3)*(cos(n*pi*x/L) from -L to 0)+(integrate (b_1*x^2+b_2*x+b_3)*(cos(n*pi*x/L) from 0 to L))