1) x^4 - 47x^2 - 98 = (x^2 - 49)(x^2 + 2) = (x-7)(x+7)(x^2+2) D = 47^2 + 4*98 = 2601 = 51^2 x1^2 = (47+51)/2 = 49 x2^2 = (47-51)/2 = -2 2)x^4 - 85x^2 + 1764 = (x^2 - 49)(x^2 - 36) = (x-7)(x+7)(x-6)(x+6) D = 7225 - 7025 = 169 = 13^2 x1^2 = (85 + 13)/2 = 49 x1^2 = (85 - 13)/2 = 36