Answer:
Option C is correct.
A number is, 25
Step-by-step explanation:
To complete the square of the given equation:
Take half of the value of the term containing x then square it,
and add and subtract that value from the left-hand side of the equation.
It should be done in the following manner:
Now, use the middle-term break to factories the expression within the parenthesis,
Use the algebraic identity:
we have;
Add 25 to both sides we get;
Therefore, you add a number 25 to complete the square.