Express 1+x^2/(1-x)(1+2x) in partial fraction .

Hence ,findthe constant term in the expansion if 1+x^2/-3x(1-x)(1+2x) in ascending power of x .

I had done the partial fraction ,the answer is 1+x^2/(1-x)(1+2x)= -1/2+2/3(1-x)+5/6(1+2x) .

so can help me solved the next step ?! thanks for help !