Answer
$-1, \ or, \ 0.25$
Work Step by Step
For the equation $4x^2 +3x-1 = 0$, we use the quadratic formula as follows
$$
x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a},
\\
a=4, \quad b=3, \quad c=-1
.$$
That is,
$$
x=\frac{-3\pm \sqrt{9+16}}{2(4) }=-1, \ or, \ 0.25
.$$
