Factor completely x^2 - 10x + 25.

a. (x - 5) (x - 5)

b. (x + 5) (x + 5)

c. (x + 5) (x - 5)

d. (x - 25) (x - 1)

We're looking for two numbers that when multiplied, give 25, and when added, give - 10.

Factoring 25 leads to 5*5 or - 5*-5. The second alternative also fits - 5+-5 = - 10.

So (x-5) (x-5) is the factorization.

The answer is a.

x^2 - 10x+25 = x*x-2*5*x+5*5 = > (x-5) (x-5)