سیگما

`Q=int 1/(x^4+1)dx`
`Q=int 1/((x^2-sqrt(2)x+1)(x^2+sqrt(2)x+1))dx`
`Q=int (Ax+B)/(x^2-sqrt(2)x+1)+(Cx+D)/(x^2+sqrt(2)x+1)dx`
`Q=sqrt(2)/8(int (2x+2sqrt(2))/(x^2+sqrt(2)x+1)dx-int (2x-2sqrt(2))/(x^2-sqrt(2)x+1)dx)`
`Q=sqrt(2)/8(ln|(x^2+sqrt(2)x+1)/(x^2-sqrt(2)x+1)|+sqrt(2)int (dx)/(x^+sqrt(2)x+1)-sqrt(2)int (dx)/(x^2-sqrt(2)x+1))`
`Q=sqrt(2)/8(ln|(x^2+sqrt(2)x+1)/(x^2-sqrt(2)x+1)|+sqrt(2)int (dx)/((x+sqrt(2)/2)^2+1/2)-sqrt(2)int (dx)/((x-sqrt(2)/2)^2+1/2))`
`Q=sqrt(2)/8(ln|(x^2+sqrt(2)x+1)/(x^2-sqrt(2)x+1)|+2arctan(1+sqrt(2)x)-2arctan(1-sqrt(2)x))`