Answer
$0.618, \ or, \ -1.618
.$
Work Step by Step
For the equation $x^2 +x-1= 0$, we use the quadratic formula as follows
$$
x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a},
\\
a=1, \quad b=1, \quad c=-1
.$$
That is, $$ x=\frac{-1\pm \sqrt{1+4}}{2(1) }=0.618, \ or, \ -1.618
.$$
