The teacher will be very surprised to see your correct solution 😉
x4-17*x2+16 = 0
16 + x4 - 17*x2 = 0
x4 = -16 - x4 / (-17*x2/x4)
x41 = -16 + 17*re(x2) + 17*I*im(x2)
x41 = 17*re(x2) + 17*i*im(x2) - 16
sum
-16 + 17*re(x2) + 17*I*im(x2)
=
-16 + 17*re(x2) + 17*I*im(x2)
product
-16 + 17*re(x2) + 17*I*im(x2)
=
-16 + 17*re(x2) + 17*I*im(x2)
-16 + 17*re(x2) + 17*i*im(x2)