The qudractic function is .

To find the x-intercept.

                                    (Substitute f (x) = 0)

The equation compare to quadratic equation, then a = 7, b = 3 and c = 1.

Quadratic formula: .

    (Substitute a = 7, b = 3 and c = 1)

              (Product of two same signs is positive)

                      (Evaluate power: )

                                  (Simplify)

                                        (Add: )

Using calculator and Evaluate square roots: .

Separate the solutions .

                (Simplify)

The solution set is .