If the polynomial function p has real coefficients and if a + bi is a zero of p, then incorrect:
your answer is incorrect. is also a zero of p. so if 2 + i is a zero of p, then incorrect:
your answer is incorrect. is also a zero of p.

Using complex numbers concepts, it is found that:

If the polynomial function P has real coefficients and if a + bi is a zero of P, then a - bi is also a zero of P. So if 2 + i is a zero of P, then 2 - i is also a zero of P.

Thus, the completed sentence is:

If the polynomial function P has real coefficients and if a + bi is a zero of P, then a - bi is also a zero of P. So if 2 + i is a zero of P, then 2 - i is also a zero of P.

A similar problem is given at link

Step-by-step explanation:

If a polynomial has real coefficients, complex zeros come in conjugate pairs.

If a+bi is a zero, then so is a-bi. (a-bi is the conjugate of a+bi)

If 2+i is a zero, then so is 2-i.