Which value must be added to the expression x2 + x to make it a perfect-square trinomial?

For this case we have the following expression:

We want to find a constant to create a perfect-square trinomial

The value of the constant is given by:

Where, b belongs to the coefficient that accompanies the term of exponent 1 in the quadratic equation.

Substituting values:

Rewriting the expression we have:

must be added to the expression to make it a perfect-square trinomial

walter needs to make at least 5 more cookies but no more than 40. 5 ≤ x ≤ 40

step-by-step explanation:

20 ≤ x + 15 ≤ 55

subtract 15 from all parts

20-15 ≤ x + 15-15 ≤ 55-15

5 ≤ x ≤ 40

this means how many more cookies he has to make

walter needs to make at least 5 more cookies, but no more than 40 cookies; 5 ≤ x ≤ 40