# How do you solve #x^2 + 6x +8= 0 # by completing the square?

##### 1 Answer

Feb 4, 2016

(see below for method)

#### Explanation:

Given:

It will be convenient (although not necessary) to move the constant to the right side as:

For the general squared binomial:

#(x+a)^2 = x^2+2a+a^2# So if

#x^2+6x#

#color(white)("XXX")# are the first two terms of an expanded squared binomial

then#a=3 and a^2=9#

and we need to add#9# (to both sides) to complete the square

#color(blue)(x^2+6x)color(red)(+9) = color(blue)(-8)color(red)(+9)#

#color(green)((x+3)^2= 1)#

If

then