Use substitution to show that the statements below are true.

1. $−3$ and $2$ are roots of the equation $x^{2} + x − 6 = 0$.

   Hint (a):

   Substitute $−3$ first for $x$. Simplify.
   Substitute $2$ next for $x$. Simplify.

2. $−1 + \sqrt { 7 }$ is a root of the equation $x^{2} + 2x − 6 = 0$.

   Hint (b):

   $(-1 + \sqrt 7)^2 + 2(-1 + \sqrt 7) -6 =0$

   $(-1 + \sqrt 7)(-1 + \sqrt 7) + 2(-1 + \sqrt 7) -6 =0$