Solve for x in the equation x squared minus 4 x minus 9 = 29.
x = 2 plus-or-minus StartRoot 42 EndRoot
x = 2 plus-or-minus StartRoot 33 EndRoot
x = 2 plus-or-minus StartRoot 34 EndRoot
x = 4 plus-or-minus StartRoot 42 EndRoot
The square root of 42 is 6.5 so you just use the square root of 42 and 2 because the perfect trinomial is x squared minus 4x+4=38+4. which is (x-2) so that is where the 2 comes from.
