We start with the given equation
[tex] x^{2} + 4 = 8 [/tex]
Now, we solve the equation, we subtract 4 on either side,
[tex] x^{2} +4 -4 = 8-4 [/tex]
[tex] x^{2} = 4 [/tex]
[tex] x = \sqrt{4} [/tex]
[tex] \sqrt{4 } = +2 and -2 [/tex]
x = +2 or -2
So, x= +2 and x =-2
Since the given conjuncture says X=-2, we can conclude that the given conjuncture is TRUE
