Final answer:
The end behavior of the function F(x) = x^2 + 4x + 3 is an upward opening graph on both ends.
Step-by-step explanation:
The end behavior of a polynomial function can be determined by examining the leading term. In the given function, F(x) = x^2 + 4x + 3, the leading term is x^2. Since the degree of the leading term is 2, we can conclude that the end behavior of the function is the same as that of a quadratic function. As x approaches positive or negative infinity, the value of x^2 increases without bound, resulting in a graph that opens upwards on both ends.