x^2+4x+4=8
-8 -8
subtract 8 from both sides
x^2+4x-4=0
now factor using quadratic formula
ax^2+bx+c=0
x= -b +-[ (sqrt (b^2-4ac))/2a ]
x=-2(1+sqrt(2))
x= 2(sqrt(2) -1)
hope that helps, hopefully you know how to plug and chug into quadratic formula. if not you can ask for help