∫x^2dx/[a^6-x^6]=(1/3)∫[a^3-x^3+a^3+x^3]dx^3/[2a^3 *(a^3-x^3)(a^3+x^3)]=(1/(6a^3)) [ ∫d(x^3+a^3)/(x^3+a^3)+∫d(x^3-a^3)/a^3-x^3)]=(1/(6a^3))ln|a^3+x^3|/|a^3-x^3|+C