Answer:
The another root of the polynomial
is 
Step-by-step explanation:
let
is a polynomial root.
Subtracting both sides by 2, we get

Squaring both sides, we get


On solving we get,

Using quadratic formula:

If one of the root of the polynomial is
; then another root by quadratic formula is 
or else we can say that irrational roots will always come in conjugate pairs.
Sso, if
is a root, then
is also a root.