Factor completely x2 − 10x + 25. (x − 5)(x − 5) (x + 5)(x + 5) (x + 5)(x − 5) (x − 25)(x − 1)

To factor a trinomial first look to the c-value (constant) and find a factor pair which adds to give the middle b-value.

25 factors
5,5
-5,-5
25, 1
-25, -1

-5 and -5 multiply to give 25 and add to give the middle b-value -10

so then the solution is: (x - 5)(x - 5)