The qudractic function is
.
To find the x-intercept.
\
(Substitute f (x) = 0)

The equation compare to quadratic equation, then a = 13, b =
16 and c =
4.
Quadratic formula:
.
(Substitute a = 13, b =
16 and c =
4)
(Product of two same signs is positive)
(Evaluate power:
)
(Simplify)
(Add: 121 + 208)
Using calculator and Evaluate square roots:
.

Separate the solutions
.
(Simplify)
(Divide:
)
The solution set is
.