Question

How do you complete the square for `x^2+2x`?

Answer 1

`x^2+2x+1 = (x+1)^2`

Explanation:

`x^2 +2x`

To complete the square means you have to add the missing constant so that the expression can be written in the form:

`(x+?)^2`

A quadratic trinomial is of the form `ax^2 +bx+c`

If `a=1`, then the missing constant can be found from `(b/2)^2`
,
`b=2" "rarr color(blue)((2/2)^2 = 1)`

`x^2 + 2x color(blue)(+1) =" "(x+1)^2`