Question

How do you solve x^2-4x=0 by completing the square ?

Answer 1

`x=0`
`x=4`

Explanation:

To complete the square, use `(b/2)^2`
`b=-4`, `(-4/2)^2=4`

Add `4` to both sides:
`x^2-4x+4= 4`

Factor:
`(x-2)^2=4`

Square root both sides:
`x-2= +-2`

`x=2+-2`

`x=0`
`x=4`