Apolynomial has one root that equals 2+i. name one other root of this polynomial.

2-i. Complex roots always come in pairs (complex conjugates)

ANSWER

One other root of this polynomial is


EXPLANATION

One property of the complex root of a polynomial is the conjugate root property.

If one root of a polynomial is

then the conjugate is also a root of this polynomial.

The conjugate of

is


Also the conjugate of


is


Therefore if

is a root of the polynomial, then its complex conjugate

is also a root of that polynomial.

The same applies to purely imaginary complex roots too.

Thus, if

is a root then its conjugate

is also a root.