Solve the equation x4−16x3+86x2−176x+105=0. If two roots being 1 and 7, Find the sum of the square of other two roots.
If 1 and 7 are the roots of the given equation.
(x−1)(x−7) are the factors of x4−16x3+86x2−176x+105=0.
Divide x4−16x3+86x2−176x+105 by x2−8x+7 and find the quotient
x2+8x+15 x2−8x+7x4−16x3+86x2−176x+105 _x4_+−8x3_−+7x2 −8x3+79x2−176x+105 +−8x3 −+64x2 +−56x 15x2−120x+105 _−15x2+_+120x −+105 0 Quotient is x2−8x+15=0,(x−3)(x−5)=0,x=3,5
Sum of the square of the square of other two roots =32+52=9+25=34.