Answer:
25.
Explanation:
To find the value that will make the left side a perfect-square trinomial, you need to find (b/2)^2. In this case, b = -10.
(-10 / 2)^2
= (-5)^2
= (-5) * (-5)
= 25
Once you add 25 to both sides, the left side becomes x^2 - 10x + 25, which is equal to (x - 5)^2.
Hope this helps!