在实属范围内分解因式：
3a^2+a-1
=3(a^2+(a/3))-1
=3(a^2+(a/3)+(1/36)-(1/36))-1
=3(a+(1/6))^2-(13/12)
=(3^(1/2)a+(3^(1/2)/6)+(13/12)^(1/2))(3^(1/2)a+(3^(1/2)/6)-(13/12)^(1/2))