To factor: Notice that when you factor it should turn out to be a binomial x binomial.
x^2-10x+25
When factoring you can look at the operation at the end right before the last digit. If the operation is positive then you will use the first operation in the binomial for factored number. For example the ending operation is positive and the first operation is subtraction so both binomial will be subtraction.
I know it would be factored (x-5)(x-5) and I can prove it by multiplying it out.
x^2 -5x-5x+25
x^2-10x+25