How do I achieve getting the answer to this?

Question

Solve by completing the square:
x^2 + 8x + 2 = 0

Answer 1

x^2 + 8x + 2 = 0
find the square of half the x coefficient and make it the constant
(8/2)^2 = 16

we already have 2 so add 14 to both sides
x^2 + 8x + 2 + 14 = 14
x^2 + 8x +16 = 14
now factor
(x + 4)^2 = 14
sqrt both sides, do not forget the negative root
x+4 = sqrt(14) or -sqrt(14)

x = -4 + sqrt(14) or -4 - sqrt(14)

x = 7.7416 or .2583

Answer 2

1. Factor out any coefficients attached to the squared term (in this case, the squared term has no coefficient, so you would skip this step).

2. Move constants to the opposite side of the equation from any terms that contain a variable (x).
~ x^2+8x = -2

3. Take HALF of the coefficient of the x-term (which is 8x in this case) and SQUARE it. Add the result to both sides of the equation.
~ half of 8 is 4
~ 4^2 is 16
~ x^2+8x+16= 14
(NOTE: on this step, if you factored out the coefficient of the squared term as in step 1, be sure to multiply the number you factored out by the result of step 3 BEFORE adding it to the opposite side of the equation.)

4. Factor the new trinomial.
~ (x+4)^2=14

5. Solve:
~(x+4)^2= 14
~x+4 = (+/-)sqrt14
~x= (+/-)sqrt(14) - 4

Answer 3

x^2+8x=-2

x^2+8x+__=-2+__

x^2+8x+16=-2+16 or 14

(x+4)^2=14

x+4=+or - square root of 14

x= + or - square root of 14 - 4

Answer 4

x^2+8x+2=(x+4)^2-14
so
(x+4)^2= 14 and x+4 = +-sqrt14
x=-4+-sqrt14

Answer 5

http://www.purplemath.com/modules/sqrquad.htm