x^4 + 4bx^3 + (a^2 + 4b^2 + l^2)x^2 + 2(b(a^2+l^2)-m*l^2)x + a^2l^2 = 0
For some specific values of the unknown coefficients we can get the root. But how could we get the roots of the equation for unknown values of the coefficients ,i.e., how could we get the roots for any values of the coefficients ?