To complete the expression x² + 4x, we need to find a number that will allow us to write it in a perfect square form. This involves finding a constant that helps complete the square.
To do this, take the coefficient of the linear term (which is 4 in this case), divide it by 2, and then square the result:
- 4 divided by 2 gives us 2.
- Squaring 2 results in 4.
Therefore, the number that should be added to the expression x² + 4x is 4. This means we rewrite the expression as:
x² + 4x + 4 = (x + 2)².
By adding 4, we have transformed the quadratic expression into a perfect square trinomial, making it easier to work with in the future.