Question

How do you solve `x^2 + 16x = 0` by completing the square?

Answer 1

If `x^2 + 16x` are the first two terms of an squared expression
`(x+a)^2 = x^2+2ax+a^2`
then `a= 8`

`x^2+16x = 0`
can be written as
`x^2+16x+8^2 = 8^2`

#(x+8)^2 = 64

Taking the square root
`x+8 = +-8`

and
`x= 0` or `x=16`