What is the factored form of a fourth degree polynomial function with coefficients that has -3,1and 1+5i

Can someone me with this problem i don't understand i need

F(x)=x/2-2 and g(x)=2x^2+x-3 find (f+g)(x)

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?