Answer:
(x-7)(x-3)
Explanation:
The factored form of f(x)=x^2-10x+21 is (x-7)(x-3). In order to find the factored form, you have to find what values add to -10, yet multiply to 21. So, the values that add to -10 and multiply to 21 are -7 and -3. x and x multiply to x^2.
In conclusion, the factored form of f(x)=x^2-10x+21 is (x-7)(x-3).