Answer
$-1, \ or, \ - 0.25$
Work Step by Step
For the equation $4x^2 +5x+1= 0$, we use the quadratic formula as follows
$$
x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a},
\\
a=4, \quad b=5, \quad c=1
.$$
That is, $$ x=\frac{-5\pm \sqrt{25-16}}{2(4) }=-1, \ or, \ - 0.25
.$$
