Using complex numbers concepts, it is found that the statement is false.
When a complex number is a root of a polynomial function, it's conjugate also has to be.
A complex number has the format , and it's conjugate is .
In this problem:
Real root -3.
Complex-conjugate roots 1 + i and 1 - i.
Complex root -3 + 7i.
The conjugate of -3 + 7i also has to be a root, which would make the polynomial of the 5th degree, as it would have 5 roots, thus, the statement is false.