LOL.
consider (x+a)(x+b)(x+c)(x+d) = x^4 - 4x^3 + 5x^2 -2x -2
equating constants abcd = -2
So the four roots a,b,c,d must multiply to equal -2
NOW if they were rational, the only numbers capable of doing so are 1,-1,2,-2!
basically u sub those four nubmers in the equation...