Question 1061041

I have a problem and I have a solution too but don't understand one of the steps.

This is the problem :

(Sqrt(2) – 1) is a root of  x2 + bx + c = 0, where b, c ∈ ℤ.   Find the value of b and the value of c and hence, find the other root. 
<pre>Other root: {{{highlight_green(- 1 - sqrt(2))}}}
{{{highlight_green(matrix(1,4, "Equation:", x^2 + 2x - 1, so, system(a = 1, b = 2, c = - 1)))}}}