When 1+i,1−i are the roots, then Sum of the roots =1+i+1−i=2 and product of the roots =1+1=2 The equation is x2−2x+2=0 When 1−√2,1+√2 are the roots, then Sum of the roots =1−√2+1+√2=2 Product of the roots =1−2=−1 The equation is x2−2x−1=0 The bi-quadratic equation is (x2−2x+2)(x2−2x−1)=0 (x4−(2+2)x3=(−1+4+2)x2. =(2−4)x−2=0 ⇒‌‌x4−4x3+5x2−2x−2=0