Question

How do you solve by completing the square: `4x^2 + 8x + 20 = 0`?

Answer 1

Try this:
`4x^2+8x=-20`
`x^2+8/4x=-20/4`
`x^2+2x=-5`
`x^2+2x+1-1=-5`
`(x+1)^2=-5+1`
`(x+1)^2=-4`
`x+1=+-sqrt(-4)` NEGATIVE ROOT!
If you already saw complex numbers you have:
`x+1=+-[sqrt(4)sqrt(-1)]`
`x=-1+-2i`