The quadratic function is .
To find the x-intercept.
\ (Substitute f (x) = 0)
The equation compare to quadratic equation, then a = 1, b = 4 and c = 7.
Quadratic formula: .
(Substitute a = 1, b = 4 and c = 7)
(Evaluate power:
)
(Simplify)
(Subtract:
) \ \
The solution is .