If using the method of completing the square to solve the quadratic equation x^2-15x-10=0, which number would have to be added to complete the square

Step-by-step explanation:

So to complete the square we need to add (and subtract) the number  

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.