The roots of x2 − ( ) + 34 are 5 ± 3i.

Use quadratic formula
if you had ax^2+bx+c=0, then
x=
a=1
b=?
c=34
subsitute
=5+/-3i
=5+/-3i
make 5+/-3 into fraction over 2,(10+/-6i)/2
=(10+/-6i)/2
multiply both sides by 2
=10+/-6i
we conclude that -b=10
b=-10

ok so equaton is
x^2-10x+34