Question

How do you solve by completing the square: `x^2 +2x - 24 =0`?

Answer 1

Ad `24` to both sides to clear the constant from the left side of the equation
`x^2 + 2x = 24`

Remember that `(x+1)^2 = x^2 + 2x +1`
so add `1` to both sides in order to complete the square on the left side
`x^2+2x+1 = 24 +1`

`(x+1)^2 = 25`

Take the square root of both sides
`x+1= +-5`

Giving the solutions
`x= 4` and `x=-6`