Question

How do you solve by completing the square `2x^2+4x+12=0`?

Answer 1

Start by writing:
`2x^2+4x=-12`
`x^2+4/2x=-12/2`
`x^2+2x=-6`
`x^2+2x+1-1=-6`
`(x+1)^2=-6+1`
`(x+1)^2=-5`
`(x+1)=+-sqrt(-5)`
You have a negative squre root!
Did you see complex numbers yet?
If NOT stop here and say "no real solutions".
If YES:
`x=-1+-isqrt(5)`