A fourth degree polynomial that has five terms could have five linear factors.?

No, if it is of degree 4, it can have 4 linear factors, regardless of the number of terms.For example, x squared + 5x + 6 = (x+3)(x+2). The unfactored polynomial has three terms, and is of degree 2. Similarly, you can multiply four linear terms together; and you will get a polynomial of degree 4, which has up to 5 terms.